diff --git a/cmds/atrace/atrace.cpp b/cmds/atrace/atrace.cpp
index 9cdc9e9..a48dab9 100644
--- a/cmds/atrace/atrace.cpp
+++ b/cmds/atrace/atrace.cpp
@@ -481,8 +481,8 @@
         newClock = "global";
     }
 
-    size_t begin = clockStr.find("[") + 1;
-    size_t end = clockStr.find("]");
+    size_t begin = clockStr.find('[') + 1;
+    size_t end = clockStr.find(']');
     if (newClock.compare(0, std::string::npos, clockStr, begin, end-begin) == 0) {
         return true;
     }
@@ -543,7 +543,7 @@
     auto listRet = sm->list([&](const auto &interfaces) {
         for (size_t i = 0; i < interfaces.size(); i++) {
             string fqInstanceName = interfaces[i];
-            string::size_type n = fqInstanceName.find("/");
+            string::size_type n = fqInstanceName.find('/');
             if (n == std::string::npos || interfaces[i].size() == n+1)
                 continue;
             hidl_string fqInterfaceName = fqInstanceName.substr(0, n);
diff --git a/cmds/dumpstate/dumpstate.cpp b/cmds/dumpstate/dumpstate.cpp
index 657323d..9e77e8f 100644
--- a/cmds/dumpstate/dumpstate.cpp
+++ b/cmds/dumpstate/dumpstate.cpp
@@ -691,7 +691,7 @@
     std::string valid_name = entry_name;
 
     // Rename extension if necessary.
-    size_t idx = entry_name.rfind(".");
+    size_t idx = entry_name.rfind('.');
     if (idx != std::string::npos) {
         std::string extension = entry_name.substr(idx);
         std::transform(extension.begin(), extension.end(), extension.begin(), ::tolower);
@@ -1432,7 +1432,7 @@
     return true;
 }
 
-static std::string SHA256_file_hash(std::string filepath) {
+static std::string SHA256_file_hash(const std::string& filepath) {
     android::base::unique_fd fd(TEMP_FAILURE_RETRY(open(filepath.c_str(), O_RDONLY | O_NONBLOCK
             | O_CLOEXEC | O_NOFOLLOW)));
     if (fd == -1) {
diff --git a/cmds/dumpsys/dumpsys.cpp b/cmds/dumpsys/dumpsys.cpp
index f0e7200..73c7f18 100644
--- a/cmds/dumpsys/dumpsys.cpp
+++ b/cmds/dumpsys/dumpsys.cpp
@@ -176,7 +176,7 @@
     }
 
     for (size_t i = 0; i < N; i++) {
-        String16 service_name = std::move(services[i]);
+        const String16& service_name = std::move(services[i]);
         if (IsSkipped(skippedServices, service_name)) continue;
 
         sp<IBinder> service = sm_->checkService(service_name);
diff --git a/cmds/dumpsys/tests/dumpsys_test.cpp b/cmds/dumpsys/tests/dumpsys_test.cpp
index 66beb6d..5ca2b57 100644
--- a/cmds/dumpsys/tests/dumpsys_test.cpp
+++ b/cmds/dumpsys/tests/dumpsys_test.cpp
@@ -95,7 +95,7 @@
     }
     int i = 0;
     std::ostringstream actual_stream, expected_stream;
-    for (String16 actual : arg) {
+    for (const String16& actual : arg) {
         std::string actual_str = String8(actual).c_str();
         std::string expected_str = expected[i];
         actual_stream << "'" << actual_str << "' ";
diff --git a/cmds/installd/CacheTracker.cpp b/cmds/installd/CacheTracker.cpp
index 3eb39b9..ea0cd9e 100644
--- a/cmds/installd/CacheTracker.cpp
+++ b/cmds/installd/CacheTracker.cpp
@@ -60,7 +60,7 @@
 
     ATRACE_BEGIN("loadStats tree");
     cacheUsed = 0;
-    for (auto path : mDataPaths) {
+    for (const auto& path : mDataPaths) {
         auto cachePath = read_path_inode(path, "cache", kXattrInodeCache);
         auto codeCachePath = read_path_inode(path, "code_cache", kXattrInodeCodeCache);
         calculate_tree_size(cachePath, &cacheUsed);
@@ -170,7 +170,7 @@
     items.clear();
 
     ATRACE_BEGIN("loadItems");
-    for (auto path : mDataPaths) {
+    for (const auto& path : mDataPaths) {
         loadItemsFrom(read_path_inode(path, "cache", kXattrInodeCache));
         loadItemsFrom(read_path_inode(path, "code_cache", kXattrInodeCodeCache));
     }
diff --git a/cmds/installd/InstalldNativeService.cpp b/cmds/installd/InstalldNativeService.cpp
index 8a79ee1..af7455a 100644
--- a/cmds/installd/InstalldNativeService.cpp
+++ b/cmds/installd/InstalldNativeService.cpp
@@ -1349,7 +1349,7 @@
         const std::vector<std::string>& codePaths, std::vector<int64_t>* _aidl_return) {
     ENFORCE_UID(AID_SYSTEM);
     CHECK_ARGUMENT_UUID(uuid);
-    for (auto packageName : packageNames) {
+    for (const auto& packageName : packageNames) {
         CHECK_ARGUMENT_PACKAGE_NAME(packageName);
     }
     // NOTE: Locking is relaxed on this method, since it's limited to
@@ -1388,7 +1388,7 @@
     }
 
     ATRACE_BEGIN("obb");
-    for (auto packageName : packageNames) {
+    for (const auto& packageName : packageNames) {
         auto obbCodePath = create_data_media_obb_path(uuid_, packageName.c_str());
         calculate_tree_size(obbCodePath, &extStats.codeSize);
     }
@@ -1396,7 +1396,7 @@
 
     if (flags & FLAG_USE_QUOTA && appId >= AID_APP_START) {
         ATRACE_BEGIN("code");
-        for (auto codePath : codePaths) {
+        for (const auto& codePath : codePaths) {
             calculate_tree_size(codePath, &stats.codeSize, -1,
                     multiuser_get_shared_gid(0, appId));
         }
@@ -1407,7 +1407,7 @@
         ATRACE_END();
     } else {
         ATRACE_BEGIN("code");
-        for (auto codePath : codePaths) {
+        for (const auto& codePath : codePaths) {
             calculate_tree_size(codePath, &stats.codeSize);
         }
         ATRACE_END();
diff --git a/cmds/installd/dexopt.cpp b/cmds/installd/dexopt.cpp
index 2b2725f..28b2240 100644
--- a/cmds/installd/dexopt.cpp
+++ b/cmds/installd/dexopt.cpp
@@ -28,6 +28,7 @@
 #include <unistd.h>
 
 #include <android-base/logging.h>
+#include <android-base/properties.h>
 #include <android-base/stringprintf.h>
 #include <android-base/strings.h>
 #include <android-base/unique_fd.h>
@@ -67,6 +68,10 @@
     return unique_fd(-1);
 }
 
+static bool is_debug_runtime() {
+    return android::base::GetProperty("persist.sys.dalvik.vm.lib.2", "") == "libartd.so";
+}
+
 static bool clear_profile(const std::string& profile) {
     unique_fd ufd(open(profile.c_str(), O_WRONLY | O_NOFOLLOW | O_CLOEXEC));
     if (ufd.get() < 0) {
@@ -267,7 +272,8 @@
                 dex2oat_large_app_threshold);
     }
 
-    static const char* DEX2OAT_BIN = "/system/bin/dex2oat";
+    // If the runtime was requested to use libartd.so, we'll run dex2oatd, otherwise dex2oat.
+    const char* dex2oat_bin = is_debug_runtime() ? "/system/bin/dex2oatd" : "/system/bin/dex2oat";
 
     static const char* RUNTIME_ARG = "--runtime-arg";
 
@@ -376,7 +382,7 @@
     }
 
 
-    ALOGV("Running %s in=%s out=%s\n", DEX2OAT_BIN, relative_input_file_name, output_file_name);
+    ALOGV("Running %s in=%s out=%s\n", dex2oat_bin, relative_input_file_name, output_file_name);
 
     const char* argv[9  // program name, mandatory arguments and the final NULL
                      + (have_dex2oat_isa_variant ? 1 : 0)
@@ -397,7 +403,7 @@
                      + (has_base_dir ? 1 : 0)
                      + (have_dex2oat_large_app_threshold ? 1 : 0)];
     int i = 0;
-    argv[i++] = DEX2OAT_BIN;
+    argv[i++] = dex2oat_bin;
     argv[i++] = zip_fd_arg;
     argv[i++] = zip_location_arg;
     argv[i++] = input_vdex_fd_arg;
@@ -463,8 +469,8 @@
     // Do not add after dex2oat_flags, they should override others for debugging.
     argv[i] = NULL;
 
-    execv(DEX2OAT_BIN, (char * const *)argv);
-    ALOGE("execv(%s) failed: %s\n", DEX2OAT_BIN, strerror(errno));
+    execv(dex2oat_bin, (char * const *)argv);
+    ALOGE("execv(%s) failed: %s\n", dex2oat_bin, strerror(errno));
 }
 
 /*
@@ -643,7 +649,7 @@
 static void run_profman_merge(const std::vector<unique_fd>& profiles_fd,
         const unique_fd& reference_profile_fd) {
     static const size_t MAX_INT_LEN = 32;
-    static const char* PROFMAN_BIN = "/system/bin/profman";
+    const char* profman_bin = is_debug_runtime() ? "/system/bin/profmand" : "/system/bin/profman";
 
     std::vector<std::string> profile_args(profiles_fd.size());
     char profile_buf[strlen("--profile-file-fd=") + MAX_INT_LEN];
@@ -657,7 +663,7 @@
     // program name, reference profile fd, the final NULL and the profile fds
     const char* argv[3 + profiles_fd.size()];
     int i = 0;
-    argv[i++] = PROFMAN_BIN;
+    argv[i++] = profman_bin;
     argv[i++] = reference_profile_arg;
     for (size_t k = 0; k < profile_args.size(); k++) {
         argv[i++] = profile_args[k].c_str();
@@ -665,8 +671,8 @@
     // Do not add after dex2oat_flags, they should override others for debugging.
     argv[i] = NULL;
 
-    execv(PROFMAN_BIN, (char * const *)argv);
-    ALOGE("execv(%s) failed: %s\n", PROFMAN_BIN, strerror(errno));
+    execv(profman_bin, (char * const *)argv);
+    ALOGE("execv(%s) failed: %s\n", profman_bin, strerror(errno));
     exit(68);   /* only get here on exec failure */
 }
 
@@ -1364,7 +1370,10 @@
 // the profile has changed.
 static void exec_dexoptanalyzer(const std::string& dex_file, const std::string& instruction_set,
         const std::string& compiler_filter, bool profile_was_updated, bool downgrade) {
-    static const char* DEXOPTANALYZER_BIN = "/system/bin/dexoptanalyzer";
+    const char* dexoptanalyzer_bin =
+            is_debug_runtime()
+                    ? "/system/bin/dexoptanalyzerd"
+                    : "/system/bin/dexoptanalyzer";
     static const unsigned int MAX_INSTRUCTION_SET_LEN = 7;
 
     if (instruction_set.size() >= MAX_INSTRUCTION_SET_LEN) {
@@ -1385,7 +1394,7 @@
         (downgrade ? 1 : 0);
     const char* argv[argc];
     int i = 0;
-    argv[i++] = DEXOPTANALYZER_BIN;
+    argv[i++] = dexoptanalyzer_bin;
     argv[i++] = dex_file_arg.c_str();
     argv[i++] = isa_arg.c_str();
     argv[i++] = compiler_filter_arg.c_str();
@@ -1397,8 +1406,8 @@
     }
     argv[i] = NULL;
 
-    execv(DEXOPTANALYZER_BIN, (char * const *)argv);
-    ALOGE("execv(%s) failed: %s\n", DEXOPTANALYZER_BIN, strerror(errno));
+    execv(dexoptanalyzer_bin, (char * const *)argv);
+    ALOGE("execv(%s) failed: %s\n", dexoptanalyzer_bin, strerror(errno));
 }
 
 // Prepares the oat dir for the secondary dex files.
diff --git a/cmds/servicemanager/binder.c b/cmds/servicemanager/binder.c
index 93a18fc..fade8cf 100644
--- a/cmds/servicemanager/binder.c
+++ b/cmds/servicemanager/binder.c
@@ -514,7 +514,7 @@
         return;
 
     obj->flags = 0x7f | FLAT_BINDER_FLAG_ACCEPTS_FDS;
-    obj->type = BINDER_TYPE_BINDER;
+    obj->hdr.type = BINDER_TYPE_BINDER;
     obj->binder = (uintptr_t)ptr;
     obj->cookie = 0;
 }
@@ -532,7 +532,7 @@
         return;
 
     obj->flags = 0x7f | FLAT_BINDER_FLAG_ACCEPTS_FDS;
-    obj->type = BINDER_TYPE_HANDLE;
+    obj->hdr.type = BINDER_TYPE_HANDLE;
     obj->handle = handle;
     obj->cookie = 0;
 }
@@ -649,7 +649,7 @@
     if (!obj)
         return 0;
 
-    if (obj->type == BINDER_TYPE_HANDLE)
+    if (obj->hdr.type == BINDER_TYPE_HANDLE)
         return obj->handle;
 
     return 0;
diff --git a/cmds/surfacereplayer/replayer/Replayer.cpp b/cmds/surfacereplayer/replayer/Replayer.cpp
index 35b63ec..2b5389b 100644
--- a/cmds/surfacereplayer/replayer/Replayer.cpp
+++ b/cmds/surfacereplayer/replayer/Replayer.cpp
@@ -505,7 +505,7 @@
     ALOGV("Setting Transparent Region Hint");
     Region re = Region();
 
-    for (auto r : trhc.region()) {
+    for (const auto& r : trhc.region()) {
         Rect rect = Rect(r.left(), r.top(), r.right(), r.bottom());
         re.merge(rect);
     }
diff --git a/include/android/sensor.h b/include/android/sensor.h
index 7f46087..a88733c 100644
--- a/include/android/sensor.h
+++ b/include/android/sensor.h
@@ -388,13 +388,13 @@
 #endif
 
 #if __ANDROID_API__ >= __ANDROID_API_O__
-/*
+/**
  * Get a reference to the sensor manager. ASensorManager is a singleton
  * per package as different packages may have access to different sensors.
  *
  * Example:
  *
- *    ASensorManager* sensorManager = ASensorManager_getInstanceForPackage("foo.bar.baz");
+ *     ASensorManager* sensorManager = ASensorManager_getInstanceForPackage("foo.bar.baz");
  *
  */
 ASensorManager* ASensorManager_getInstanceForPackage(const char* packageName);
@@ -503,14 +503,12 @@
  * {@link ASensor_isDirectChannelTypeSupported}, respectively.
  *
  * Example:
- * \code{.cpp}
- *      ASensorManager *manager = ...;
- *      ASensor *sensor = ...;
- *      int channelId = ...;
  *
- *      ASensorManager_configureDirectReport(
- *              manager, sensor, channel_id, ASENSOR_DIRECT_RATE_FAST);
- * \endcode
+ *     ASensorManager *manager = ...;
+ *     ASensor *sensor = ...;
+ *     int channelId = ...;
+ *
+ *     ASensorManager_configureDirectReport(manager, sensor, channel_id, ASENSOR_DIRECT_RATE_FAST);
  *
  * \param manager   the {@link ASensorManager} instance obtained from
  *                  {@link ASensorManager_getInstanceForPackage}.
@@ -530,50 +528,86 @@
 /*****************************************************************************/
 
 /**
- * Enable the selected sensor with a specified sampling period and max batch report latency.
- * Returns a negative error code on failure.
- * Note: To disable the selected sensor, use ASensorEventQueue_disableSensor() same as before.
+ * Enable the selected sensor with sampling and report parameters
+ *
+ * Enable the selected sensor at a specified sampling period and max batch report latency.
+ * To disable  sensor, use {@link ASensorEventQueue_disableSensor}.
+ *
+ * \param queue {@link ASensorEventQueue} for sensor event to be report to.
+ * \param sensor {@link ASensor} to be enabled.
+ * \param samplingPeriodUs sampling period of sensor in microseconds.
+ * \param maxBatchReportLatencyus maximum time interval between two batch of sensor events are
+ *                                delievered in microseconds. For sensor streaming, set to 0.
+ * \return 0 on success or a negative error code on failure.
  */
 int ASensorEventQueue_registerSensor(ASensorEventQueue* queue, ASensor const* sensor,
         int32_t samplingPeriodUs, int64_t maxBatchReportLatencyUs);
 
 /**
- * Enable the selected sensor. Returns a negative error code on failure.
+ * Enable the selected sensor at default sampling rate.
+ *
+ * Start event reports of a sensor to specified sensor event queue at a default rate.
+ *
+ * \param queue {@link ASensorEventQueue} for sensor event to be report to.
+ * \param sensor {@link ASensor} to be enabled.
+ *
+ * \return 0 on success or a negative error code on failure.
  */
 int ASensorEventQueue_enableSensor(ASensorEventQueue* queue, ASensor const* sensor);
 
 /**
- * Disable the selected sensor. Returns a negative error code on failure.
+ * Disable the selected sensor.
+ *
+ * Stop event reports from the sensor to specified sensor event queue.
+ *
+ * \param queue {@link ASensorEventQueue} to be changed
+ * \param sensor {@link ASensor} to be disabled
+ * \return 0 on success or a negative error code on failure.
  */
 int ASensorEventQueue_disableSensor(ASensorEventQueue* queue, ASensor const* sensor);
 
 /**
  * Sets the delivery rate of events in microseconds for the given sensor.
+ *
+ * This function has to be called after {@link ASensorEventQueue_enableSensor}.
  * Note that this is a hint only, generally event will arrive at a higher
  * rate. It is an error to set a rate inferior to the value returned by
  * ASensor_getMinDelay().
- * Returns a negative error code on failure.
+ *
+ * \param queue {@link ASensorEventQueue} to which sensor event is delivered.
+ * \param sensor {@link ASensor} of which sampling rate to be updated.
+ * \param usec sensor sampling period (1/sampling rate) in microseconds
+ * \return 0 on sucess or a negative error code on failure.
  */
 int ASensorEventQueue_setEventRate(ASensorEventQueue* queue, ASensor const* sensor, int32_t usec);
 
 /**
- * Returns true if there are one or more events available in the
- * sensor queue.  Returns 1 if the queue has events; 0 if
- * it does not have events; and a negative value if there is an error.
+ * Determine if a sensor event queue has pending event to be processed.
+ *
+ * \param queue {@link ASensorEventQueue} to be queried
+ * \return 1 if the queue has events; 0 if it does not have events;
+ *         or a negative value if there is an error.
  */
 int ASensorEventQueue_hasEvents(ASensorEventQueue* queue);
 
 /**
- * Returns the next available events from the queue.  Returns a negative
- * value if no events are available or an error has occurred, otherwise
- * the number of events returned.
+ * Retrieve pending events in sensor event queue
+ *
+ * Retrieve next available events from the queue to a specified event array.
+ *
+ * \param queue {@link ASensorEventQueue} to get events from
+ * \param events pointer to an array of {@link ASensorEvents}.
+ * \param count max number of event that can be filled into array event.
+ * \return number of events returned on success; negative error code when
+ *         no events are pending or an error has occurred.
  *
  * Examples:
- *   ASensorEvent event;
- *   ssize_t numEvent = ASensorEventQueue_getEvents(queue, &event, 1);
  *
- *   ASensorEvent eventBuffer[8];
- *   ssize_t numEvent = ASensorEventQueue_getEvents(queue, eventBuffer, 8);
+ *     ASensorEvent event;
+ *     ssize_t numEvent = ASensorEventQueue_getEvents(queue, &event, 1);
+ *
+ *     ASensorEvent eventBuffer[8];
+ *     ssize_t numEvent = ASensorEventQueue_getEvents(queue, eventBuffer, 8);
  *
  */
 ssize_t ASensorEventQueue_getEvents(ASensorEventQueue* queue, ASensorEvent* events, size_t count);
diff --git a/libs/binder/Parcel.cpp b/libs/binder/Parcel.cpp
index e22179b..84ca3c0 100644
--- a/libs/binder/Parcel.cpp
+++ b/libs/binder/Parcel.cpp
@@ -104,7 +104,7 @@
 void acquire_object(const sp<ProcessState>& proc,
     const flat_binder_object& obj, const void* who, size_t* outAshmemSize)
 {
-    switch (obj.type) {
+    switch (obj.hdr.type) {
         case BINDER_TYPE_BINDER:
             if (obj.binder) {
                 LOG_REFS("Parcel %p acquiring reference on local %p", who, obj.cookie);
@@ -140,7 +140,7 @@
         }
     }
 
-    ALOGD("Invalid object type 0x%08x", obj.type);
+    ALOGD("Invalid object type 0x%08x", obj.hdr.type);
 }
 
 void acquire_object(const sp<ProcessState>& proc,
@@ -152,7 +152,7 @@
 static void release_object(const sp<ProcessState>& proc,
     const flat_binder_object& obj, const void* who, size_t* outAshmemSize)
 {
-    switch (obj.type) {
+    switch (obj.hdr.type) {
         case BINDER_TYPE_BINDER:
             if (obj.binder) {
                 LOG_REFS("Parcel %p releasing reference on local %p", who, obj.cookie);
@@ -191,7 +191,7 @@
         }
     }
 
-    ALOGE("Invalid object type 0x%08x", obj.type);
+    ALOGE("Invalid object type 0x%08x", obj.hdr.type);
 }
 
 void release_object(const sp<ProcessState>& proc,
@@ -227,17 +227,17 @@
                 ALOGE("null proxy");
             }
             const int32_t handle = proxy ? proxy->handle() : 0;
-            obj.type = BINDER_TYPE_HANDLE;
+            obj.hdr.type = BINDER_TYPE_HANDLE;
             obj.binder = 0; /* Don't pass uninitialized stack data to a remote process */
             obj.handle = handle;
             obj.cookie = 0;
         } else {
-            obj.type = BINDER_TYPE_BINDER;
+            obj.hdr.type = BINDER_TYPE_BINDER;
             obj.binder = reinterpret_cast<uintptr_t>(local->getWeakRefs());
             obj.cookie = reinterpret_cast<uintptr_t>(local);
         }
     } else {
-        obj.type = BINDER_TYPE_BINDER;
+        obj.hdr.type = BINDER_TYPE_BINDER;
         obj.binder = 0;
         obj.cookie = 0;
     }
@@ -261,12 +261,12 @@
                     ALOGE("null proxy");
                 }
                 const int32_t handle = proxy ? proxy->handle() : 0;
-                obj.type = BINDER_TYPE_WEAK_HANDLE;
+                obj.hdr.type = BINDER_TYPE_WEAK_HANDLE;
                 obj.binder = 0; /* Don't pass uninitialized stack data to a remote process */
                 obj.handle = handle;
                 obj.cookie = 0;
             } else {
-                obj.type = BINDER_TYPE_WEAK_BINDER;
+                obj.hdr.type = BINDER_TYPE_WEAK_BINDER;
                 obj.binder = reinterpret_cast<uintptr_t>(binder.get_refs());
                 obj.cookie = reinterpret_cast<uintptr_t>(binder.unsafe_get());
             }
@@ -281,13 +281,13 @@
         // but we can't do that with the different reference counting
         // implementation we are using.
         ALOGE("Unable to unflatten Binder weak reference!");
-        obj.type = BINDER_TYPE_BINDER;
+        obj.hdr.type = BINDER_TYPE_BINDER;
         obj.binder = 0;
         obj.cookie = 0;
         return finish_flatten_binder(NULL, obj, out);
 
     } else {
-        obj.type = BINDER_TYPE_BINDER;
+        obj.hdr.type = BINDER_TYPE_BINDER;
         obj.binder = 0;
         obj.cookie = 0;
         return finish_flatten_binder(NULL, obj, out);
@@ -307,7 +307,7 @@
     const flat_binder_object* flat = in.readObject(false);
 
     if (flat) {
-        switch (flat->type) {
+        switch (flat->hdr.type) {
             case BINDER_TYPE_BINDER:
                 *out = reinterpret_cast<IBinder*>(flat->cookie);
                 return finish_unflatten_binder(NULL, *flat, in);
@@ -326,7 +326,7 @@
     const flat_binder_object* flat = in.readObject(false);
 
     if (flat) {
-        switch (flat->type) {
+        switch (flat->hdr.type) {
             case BINDER_TYPE_BINDER:
                 *out = reinterpret_cast<IBinder*>(flat->cookie);
                 return finish_unflatten_binder(NULL, *flat, in);
@@ -543,7 +543,7 @@
                 = reinterpret_cast<flat_binder_object*>(mData + off);
             acquire_object(proc, *flat, this, &mOpenAshmemSize);
 
-            if (flat->type == BINDER_TYPE_FD) {
+            if (flat->hdr.type == BINDER_TYPE_FD) {
                 // If this is a file descriptor, we need to dup it so the
                 // new Parcel now owns its own fd, and can declare that we
                 // officially know we have fds.
@@ -1152,7 +1152,7 @@
 status_t Parcel::writeFileDescriptor(int fd, bool takeOwnership)
 {
     flat_binder_object obj;
-    obj.type = BINDER_TYPE_FD;
+    obj.hdr.type = BINDER_TYPE_FD;
     obj.flags = 0x7f | FLAT_BINDER_FLAG_ACCEPTS_FDS;
     obj.binder = 0; /* Don't pass uninitialized stack data to a remote process */
     obj.handle = fd;
@@ -1310,7 +1310,7 @@
         *reinterpret_cast<flat_binder_object*>(mData+mDataPos) = val;
 
         // remember if it's a file descriptor
-        if (val.type == BINDER_TYPE_FD) {
+        if (val.hdr.type == BINDER_TYPE_FD) {
             if (!mAllowFds) {
                 // fail before modifying our object index
                 return FDS_NOT_ALLOWED;
@@ -2132,7 +2132,7 @@
 {
     const flat_binder_object* flat = readObject(true);
 
-    if (flat && flat->type == BINDER_TYPE_FD) {
+    if (flat && flat->hdr.type == BINDER_TYPE_FD) {
         return flat->handle;
     }
 
@@ -2325,7 +2325,7 @@
         i--;
         const flat_binder_object* flat
             = reinterpret_cast<flat_binder_object*>(mData+mObjects[i]);
-        if (flat->type == BINDER_TYPE_FD) {
+        if (flat->hdr.type == BINDER_TYPE_FD) {
             //ALOGI("Closing fd: %ld", flat->handle);
             close(flat->handle);
         }
@@ -2397,7 +2397,7 @@
             const flat_binder_object* flat
                 = reinterpret_cast<const flat_binder_object*>(DATA+OBJS[i]);
             to << endl << "Object #" << i << " @ " << (void*)OBJS[i] << ": "
-                << TypeCode(flat->type & 0x7f7f7f00)
+                << TypeCode(flat->hdr.type & 0x7f7f7f00)
                 << " = " << flat->binder;
         }
     } else {
@@ -2618,7 +2618,7 @@
             for (size_t i=objectsSize; i<mObjectsSize; i++) {
                 const flat_binder_object* flat
                     = reinterpret_cast<flat_binder_object*>(mData+mObjects[i]);
-                if (flat->type == BINDER_TYPE_FD) {
+                if (flat->hdr.type == BINDER_TYPE_FD) {
                     // will need to rescan because we may have lopped off the only FDs
                     mFdsKnown = false;
                 }
@@ -2728,7 +2728,7 @@
     for (size_t i=0; i<mObjectsSize; i++) {
         const flat_binder_object* flat
             = reinterpret_cast<const flat_binder_object*>(mData + mObjects[i]);
-        if (flat->type == BINDER_TYPE_FD) {
+        if (flat->hdr.type == BINDER_TYPE_FD) {
             hasFds = true;
             break;
         }
diff --git a/libs/binder/tests/binderLibTest.cpp b/libs/binder/tests/binderLibTest.cpp
index a04869a..71aa9a3 100644
--- a/libs/binder/tests/binderLibTest.cpp
+++ b/libs/binder/tests/binderLibTest.cpp
@@ -32,6 +32,13 @@
 
 using namespace android;
 
+static ::testing::AssertionResult IsPageAligned(void *buf) {
+    if (((unsigned long)buf & ((unsigned long)PAGE_SIZE - 1)) == 0)
+        return ::testing::AssertionSuccess();
+    else
+        return ::testing::AssertionFailure() << buf << " is not page aligned";
+}
+
 static testing::Environment* binder_env;
 static char *binderservername;
 static char *binderserversuffix;
@@ -44,6 +51,7 @@
     BINDER_LIB_TEST_REGISTER_SERVER,
     BINDER_LIB_TEST_ADD_SERVER,
     BINDER_LIB_TEST_CALL_BACK,
+    BINDER_LIB_TEST_CALL_BACK_VERIFY_BUF,
     BINDER_LIB_TEST_NOP_CALL_BACK,
     BINDER_LIB_TEST_GET_SELF_TRANSACTION,
     BINDER_LIB_TEST_GET_ID_TRANSACTION,
@@ -265,17 +273,23 @@
             pthread_mutex_unlock(&m_waitMutex);
             return ret;
         }
+        pthread_t getTriggeringThread()
+        {
+            return m_triggeringThread;
+        }
     protected:
         void triggerEvent(void) {
             pthread_mutex_lock(&m_waitMutex);
             pthread_cond_signal(&m_waitCond);
             m_eventTriggered = true;
+            m_triggeringThread = pthread_self();
             pthread_mutex_unlock(&m_waitMutex);
         };
     private:
         pthread_mutex_t m_waitMutex;
         pthread_cond_t m_waitCond;
         bool m_eventTriggered;
+        pthread_t m_triggeringThread;
 };
 
 class BinderLibTestCallBack : public BBinder, public BinderLibTestEvent
@@ -283,6 +297,7 @@
     public:
         BinderLibTestCallBack()
             : m_result(NOT_ENOUGH_DATA)
+            , m_prev_end(NULL)
         {
         }
         status_t getResult(void)
@@ -302,12 +317,35 @@
                 m_result = data.readInt32();
                 triggerEvent();
                 return NO_ERROR;
+            case BINDER_LIB_TEST_CALL_BACK_VERIFY_BUF: {
+                sp<IBinder> server;
+                int ret;
+                const uint8_t *buf = data.data();
+                size_t size = data.dataSize();
+                if (m_prev_end) {
+                    /* 64-bit kernel needs at most 8 bytes to align buffer end */
+                    EXPECT_LE((size_t)(buf - m_prev_end), (size_t)8);
+                } else {
+                    EXPECT_TRUE(IsPageAligned((void *)buf));
+                }
+
+                m_prev_end = buf + size + data.objectsCount() * sizeof(binder_size_t);
+
+                if (size > 0) {
+                    server = static_cast<BinderLibTestEnv *>(binder_env)->getServer();
+                    ret = server->transact(BINDER_LIB_TEST_INDIRECT_TRANSACTION,
+                                           data, reply);
+                    EXPECT_EQ(NO_ERROR, ret);
+                }
+                return NO_ERROR;
+            }
             default:
                 return UNKNOWN_TRANSACTION;
             }
         }
 
         status_t m_result;
+        const uint8_t *m_prev_end;
 };
 
 class TestDeathRecipient : public IBinder::DeathRecipient, public BinderLibTestEvent
@@ -606,6 +644,65 @@
     }
 }
 
+TEST_F(BinderLibTest, DeathNotificationThread)
+{
+    status_t ret;
+    sp<BinderLibTestCallBack> callback;
+    sp<IBinder> target = addServer();
+    ASSERT_TRUE(target != NULL);
+    sp<IBinder> client = addServer();
+    ASSERT_TRUE(client != NULL);
+
+    sp<TestDeathRecipient> testDeathRecipient = new TestDeathRecipient();
+
+    ret = target->linkToDeath(testDeathRecipient);
+    EXPECT_EQ(NO_ERROR, ret);
+
+    {
+        Parcel data, reply;
+        ret = target->transact(BINDER_LIB_TEST_EXIT_TRANSACTION, data, &reply, TF_ONE_WAY);
+        EXPECT_EQ(0, ret);
+    }
+
+    /* Make sure it's dead */
+    testDeathRecipient->waitEvent(5);
+
+    /* Now, pass the ref to another process and ask that process to
+     * call linkToDeath() on it, and wait for a response. This tests
+     * two things:
+     * 1) You still get death notifications when calling linkToDeath()
+     *    on a ref that is already dead when it was passed to you.
+     * 2) That death notifications are not directly pushed to the thread
+     *    registering them, but to the threadpool (proc workqueue) instead.
+     *
+     * 2) is tested because the thread handling BINDER_LIB_TEST_DEATH_TRANSACTION
+     * is blocked on a condition variable waiting for the death notification to be
+     * called; therefore, that thread is not available for handling proc work.
+     * So, if the death notification was pushed to the thread workqueue, the callback
+     * would never be called, and the test would timeout and fail.
+     *
+     * Note that we can't do this part of the test from this thread itself, because
+     * the binder driver would only push death notifications to the thread if
+     * it is a looper thread, which this thread is not.
+     *
+     * See b/23525545 for details.
+     */
+    {
+        Parcel data, reply;
+
+        callback = new BinderLibTestCallBack();
+        data.writeStrongBinder(target);
+        data.writeStrongBinder(callback);
+        ret = client->transact(BINDER_LIB_TEST_LINK_DEATH_TRANSACTION, data, &reply, TF_ONE_WAY);
+        EXPECT_EQ(NO_ERROR, ret);
+    }
+
+    ret = callback->waitEvent(5);
+    EXPECT_EQ(NO_ERROR, ret);
+    ret = callback->getResult();
+    EXPECT_EQ(NO_ERROR, ret);
+}
+
 TEST_F(BinderLibTest, PassFile) {
     int ret;
     int pipefd[2];
@@ -681,7 +778,7 @@
 
     const flat_binder_object *fb = reply.readObject(false);
     ASSERT_TRUE(fb != NULL);
-    EXPECT_EQ(BINDER_TYPE_HANDLE, fb->type);
+    EXPECT_EQ(BINDER_TYPE_HANDLE, fb->hdr.type);
     EXPECT_EQ(m_server, ProcessState::self()->getStrongProxyForHandle(fb->handle));
     EXPECT_EQ((binder_uintptr_t)0, fb->cookie);
     EXPECT_EQ((uint64_t)0, (uint64_t)fb->binder >> 32);
@@ -728,6 +825,25 @@
     }
 }
 
+TEST_F(BinderLibTest, CheckNoHeaderMappedInUser) {
+    status_t ret;
+    Parcel data, reply;
+    sp<BinderLibTestCallBack> callBack = new BinderLibTestCallBack();
+    for (int i = 0; i < 2; i++) {
+        BinderLibTestBundle datai;
+        datai.appendFrom(&data, 0, data.dataSize());
+
+        data.freeData();
+        data.writeInt32(1);
+        data.writeStrongBinder(callBack);
+        data.writeInt32(BINDER_LIB_TEST_CALL_BACK_VERIFY_BUF);
+
+        datai.appendTo(&data);
+    }
+    ret = m_server->transact(BINDER_LIB_TEST_INDIRECT_TRANSACTION, data, &reply);
+    EXPECT_EQ(NO_ERROR, ret);
+}
+
 class BinderLibTestService : public BBinder
 {
     public:
diff --git a/libs/gui/Android.bp b/libs/gui/Android.bp
index 3996305..21debc1 100644
--- a/libs/gui/Android.bp
+++ b/libs/gui/Android.bp
@@ -96,6 +96,7 @@
         "IProducerListener.cpp",
         "ISurfaceComposer.cpp",
         "ISurfaceComposerClient.cpp",
+        "LayerDebugInfo.cpp",
         "LayerState.cpp",
         "OccupancyTracker.cpp",
         "StreamSplitter.cpp",
diff --git a/libs/gui/BufferQueueProducer.cpp b/libs/gui/BufferQueueProducer.cpp
index 625dc5b..c5cab2d 100644
--- a/libs/gui/BufferQueueProducer.cpp
+++ b/libs/gui/BufferQueueProducer.cpp
@@ -764,7 +764,7 @@
     input.deflate(&requestedPresentTimestamp, &isAutoTimestamp, &dataSpace,
             &crop, &scalingMode, &transform, &acquireFence, &stickyTransform,
             &getFrameTimestamps);
-    Region surfaceDamage = input.getSurfaceDamage();
+    const Region& surfaceDamage = input.getSurfaceDamage();
 
     if (acquireFence == NULL) {
         BQ_LOGE("queueBuffer: fence is NULL");
diff --git a/libs/gui/ISurfaceComposer.cpp b/libs/gui/ISurfaceComposer.cpp
index 0a0d112..8e7f814 100644
--- a/libs/gui/ISurfaceComposer.cpp
+++ b/libs/gui/ISurfaceComposer.cpp
@@ -28,6 +28,7 @@
 #include <gui/IGraphicBufferProducer.h>
 #include <gui/ISurfaceComposer.h>
 #include <gui/ISurfaceComposerClient.h>
+#include <gui/LayerDebugInfo.h>
 
 #include <private/gui/LayerState.h>
 
@@ -469,6 +470,36 @@
         return result;
     }
 
+    virtual status_t getLayerDebugInfo(std::vector<LayerDebugInfo>* outLayers) const
+    {
+        if (!outLayers) {
+            return UNEXPECTED_NULL;
+        }
+
+        Parcel data, reply;
+
+        status_t err = data.writeInterfaceToken(ISurfaceComposer::getInterfaceDescriptor());
+        if (err != NO_ERROR) {
+            return err;
+        }
+
+        err = remote()->transact(BnSurfaceComposer::GET_LAYER_DEBUG_INFO, data, &reply);
+        if (err != NO_ERROR) {
+            return err;
+        }
+
+        int32_t result = 0;
+        err = reply.readInt32(&result);
+        if (err != NO_ERROR) {
+            return err;
+        }
+        if (result != NO_ERROR) {
+            return result;
+        }
+
+        outLayers->clear();
+        return reply.readParcelableVector(outLayers);
+    }
 };
 
 // Out-of-line virtual method definition to trigger vtable emission in this
@@ -763,6 +794,17 @@
             }
             return injectVSync(when);
         }
+        case GET_LAYER_DEBUG_INFO: {
+            CHECK_INTERFACE(ISurfaceComposer, data, reply);
+            std::vector<LayerDebugInfo> outLayers;
+            status_t result = getLayerDebugInfo(&outLayers);
+            reply->writeInt32(result);
+            if (result == NO_ERROR)
+            {
+                result = reply->writeParcelableVector(outLayers);
+            }
+            return result;
+        }
         default: {
             return BBinder::onTransact(code, data, reply, flags);
         }
diff --git a/libs/gui/LayerDebugInfo.cpp b/libs/gui/LayerDebugInfo.cpp
new file mode 100644
index 0000000..57ddde0
--- /dev/null
+++ b/libs/gui/LayerDebugInfo.cpp
@@ -0,0 +1,136 @@
+/*
+ * Copyright (C) 2017 The Android Open Source Project
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *      http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+#include <gui/LayerDebugInfo.h>
+
+#include <ui/DebugUtils.h>
+
+#include <binder/Parcel.h>
+
+#include <utils/String8.h>
+
+using namespace android;
+
+#define RETURN_ON_ERROR(X) do {status_t res = (X); if (res != NO_ERROR) return res;} while(false)
+
+namespace android {
+
+status_t LayerDebugInfo::writeToParcel(Parcel* parcel) const {
+    RETURN_ON_ERROR(parcel->writeCString(mName.c_str()));
+    RETURN_ON_ERROR(parcel->writeCString(mParentName.c_str()));
+    RETURN_ON_ERROR(parcel->writeCString(mType.c_str()));
+    RETURN_ON_ERROR(parcel->write(mTransparentRegion));
+    RETURN_ON_ERROR(parcel->write(mVisibleRegion));
+    RETURN_ON_ERROR(parcel->write(mSurfaceDamageRegion));
+    RETURN_ON_ERROR(parcel->writeUint32(mLayerStack));
+    RETURN_ON_ERROR(parcel->writeFloat(mX));
+    RETURN_ON_ERROR(parcel->writeFloat(mY));
+    RETURN_ON_ERROR(parcel->writeUint32(mZ));
+    RETURN_ON_ERROR(parcel->writeInt32(mWidth));
+    RETURN_ON_ERROR(parcel->writeInt32(mHeight));
+    RETURN_ON_ERROR(parcel->write(mCrop));
+    RETURN_ON_ERROR(parcel->write(mFinalCrop));
+    RETURN_ON_ERROR(parcel->writeFloat(mAlpha));
+    RETURN_ON_ERROR(parcel->writeUint32(mFlags));
+    RETURN_ON_ERROR(parcel->writeInt32(mPixelFormat));
+    RETURN_ON_ERROR(parcel->writeUint32(static_cast<uint32_t>(mDataSpace)));
+    for (size_t index = 0; index < 4; index++) {
+        RETURN_ON_ERROR(parcel->writeFloat(mMatrix[index / 2][index % 2]));
+    }
+    RETURN_ON_ERROR(parcel->writeInt32(mActiveBufferWidth));
+    RETURN_ON_ERROR(parcel->writeInt32(mActiveBufferHeight));
+    RETURN_ON_ERROR(parcel->writeInt32(mActiveBufferStride));
+    RETURN_ON_ERROR(parcel->writeInt32(mActiveBufferFormat));
+    RETURN_ON_ERROR(parcel->writeInt32(mNumQueuedFrames));
+    RETURN_ON_ERROR(parcel->writeBool(mRefreshPending));
+    RETURN_ON_ERROR(parcel->writeBool(mIsOpaque));
+    RETURN_ON_ERROR(parcel->writeBool(mContentDirty));
+    return NO_ERROR;
+}
+
+status_t LayerDebugInfo::readFromParcel(const Parcel* parcel) {
+    mName = parcel->readCString();
+    RETURN_ON_ERROR(parcel->errorCheck());
+    mParentName = parcel->readCString();
+    RETURN_ON_ERROR(parcel->errorCheck());
+    mType = parcel->readCString();
+    RETURN_ON_ERROR(parcel->errorCheck());
+    RETURN_ON_ERROR(parcel->read(mTransparentRegion));
+    RETURN_ON_ERROR(parcel->read(mVisibleRegion));
+    RETURN_ON_ERROR(parcel->read(mSurfaceDamageRegion));
+    RETURN_ON_ERROR(parcel->readUint32(&mLayerStack));
+    RETURN_ON_ERROR(parcel->readFloat(&mX));
+    RETURN_ON_ERROR(parcel->readFloat(&mY));
+    RETURN_ON_ERROR(parcel->readUint32(&mZ));
+    RETURN_ON_ERROR(parcel->readInt32(&mWidth));
+    RETURN_ON_ERROR(parcel->readInt32(&mHeight));
+    RETURN_ON_ERROR(parcel->read(mCrop));
+    RETURN_ON_ERROR(parcel->read(mFinalCrop));
+    RETURN_ON_ERROR(parcel->readFloat(&mAlpha));
+    RETURN_ON_ERROR(parcel->readUint32(&mFlags));
+    RETURN_ON_ERROR(parcel->readInt32(&mPixelFormat));
+    // \todo [2017-07-25 kraita]: Static casting mDataSpace pointer to an uint32 does work. Better ways?
+    mDataSpace = static_cast<android_dataspace>(parcel->readUint32());
+    RETURN_ON_ERROR(parcel->errorCheck());
+    for (size_t index = 0; index < 4; index++) {
+        RETURN_ON_ERROR(parcel->readFloat(&mMatrix[index / 2][index % 2]));
+    }
+    RETURN_ON_ERROR(parcel->readInt32(&mActiveBufferWidth));
+    RETURN_ON_ERROR(parcel->readInt32(&mActiveBufferHeight));
+    RETURN_ON_ERROR(parcel->readInt32(&mActiveBufferStride));
+    RETURN_ON_ERROR(parcel->readInt32(&mActiveBufferFormat));
+    RETURN_ON_ERROR(parcel->readInt32(&mNumQueuedFrames));
+    RETURN_ON_ERROR(parcel->readBool(&mRefreshPending));
+    RETURN_ON_ERROR(parcel->readBool(&mIsOpaque));
+    RETURN_ON_ERROR(parcel->readBool(&mContentDirty));
+    return NO_ERROR;
+}
+
+std::string to_string(const LayerDebugInfo& info) {
+    String8 result;
+
+    result.appendFormat("+ %s (%s)\n", info.mType.c_str(), info.mName.c_str());
+    info.mTransparentRegion.dump(result, "TransparentRegion");
+    info.mVisibleRegion.dump(result, "VisibleRegion");
+    info.mSurfaceDamageRegion.dump(result, "SurfaceDamageRegion");
+
+    result.appendFormat("      layerStack=%4d, z=%9d, pos=(%g,%g), size=(%4d,%4d), ",
+            info.mLayerStack, info.mZ, static_cast<double>(info.mX), static_cast<double>(info.mY),
+            info.mWidth, info.mHeight);
+
+    result.appendFormat("crop=%s, finalCrop=%s, ",
+            to_string(info.mCrop).c_str(), to_string(info.mFinalCrop).c_str());
+    result.appendFormat("isOpaque=%1d, invalidate=%1d, ", info.mIsOpaque, info.mContentDirty);
+    result.appendFormat("dataspace=%s, ", dataspaceDetails(info.mDataSpace).c_str());
+    result.appendFormat("pixelformat=%s, ", decodePixelFormat(info.mPixelFormat).c_str());
+    result.appendFormat("alpha=%.3f, flags=0x%08x, ",
+            static_cast<double>(info.mAlpha), info.mFlags);
+    result.appendFormat("tr=[%.2f, %.2f][%.2f, %.2f]",
+            static_cast<double>(info.mMatrix[0][0]), static_cast<double>(info.mMatrix[0][1]),
+            static_cast<double>(info.mMatrix[1][0]), static_cast<double>(info.mMatrix[1][1]));
+    result.append("\n");
+    result.appendFormat("      parent=%s\n", info.mParentName.c_str());
+    result.appendFormat("      activeBuffer=[%4ux%4u:%4u,%s],",
+            info.mActiveBufferWidth, info.mActiveBufferHeight,
+            info.mActiveBufferStride,
+            decodePixelFormat(info.mActiveBufferFormat).c_str());
+    result.appendFormat(" queued-frames=%d, mRefreshPending=%d",
+            info.mNumQueuedFrames, info.mRefreshPending);
+    result.append("\n");
+    return std::string(result.c_str());
+}
+
+} // android
diff --git a/libs/gui/include/gui/ISurfaceComposer.h b/libs/gui/include/gui/ISurfaceComposer.h
index f80ba00..b226742 100644
--- a/libs/gui/include/gui/ISurfaceComposer.h
+++ b/libs/gui/include/gui/ISurfaceComposer.h
@@ -39,6 +39,7 @@
 struct DisplayState;
 struct DisplayInfo;
 struct DisplayStatInfo;
+class LayerDebugInfo;
 class HdrCapabilities;
 class IDisplayEventConnection;
 class IGraphicBufferProducer;
@@ -195,6 +196,12 @@
     virtual status_t enableVSyncInjections(bool enable) = 0;
 
     virtual status_t injectVSync(nsecs_t when) = 0;
+
+    /* Gets the list of active layers in Z order for debugging purposes
+     *
+     * Requires the ACCESS_SURFACE_FLINGER permission.
+     */
+    virtual status_t getLayerDebugInfo(std::vector<LayerDebugInfo>* outLayers) const = 0;
 };
 
 // ----------------------------------------------------------------------------
@@ -229,6 +236,7 @@
         SET_ACTIVE_COLOR_MODE,
         ENABLE_VSYNC_INJECTIONS,
         INJECT_VSYNC,
+        GET_LAYER_DEBUG_INFO,
         CREATE_SCOPED_CONNECTION
     };
 
diff --git a/libs/gui/include/gui/LayerDebugInfo.h b/libs/gui/include/gui/LayerDebugInfo.h
new file mode 100644
index 0000000..8453e04
--- /dev/null
+++ b/libs/gui/include/gui/LayerDebugInfo.h
@@ -0,0 +1,73 @@
+/*
+ * Copyright (C) 2017 The Android Open Source Project
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *      http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+#pragma once
+
+#include <binder/Parcelable.h>
+
+#include <ui/PixelFormat.h>
+#include <ui/Region.h>
+
+#include <string>
+
+namespace android {
+
+/* Class for transporting debug info from SurfaceFlinger to authorized
+ * recipients.  The class is intended to be a data container. There are
+ * no getters or setters.
+ */
+class LayerDebugInfo : public Parcelable {
+public:
+    LayerDebugInfo() = default;
+    LayerDebugInfo(const LayerDebugInfo&) = default;
+    virtual ~LayerDebugInfo() = default;
+
+    virtual status_t writeToParcel(Parcel* parcel) const;
+    virtual status_t readFromParcel(const Parcel* parcel);
+
+    std::string mName = std::string("NOT FILLED");
+    std::string mParentName = std::string("NOT FILLED");
+    std::string mType = std::string("NOT FILLED");
+    Region mTransparentRegion = Region::INVALID_REGION;
+    Region mVisibleRegion = Region::INVALID_REGION;
+    Region mSurfaceDamageRegion = Region::INVALID_REGION;
+    uint32_t mLayerStack = 0;
+    float mX = 0.f;
+    float mY = 0.f;
+    uint32_t mZ = 0 ;
+    int32_t mWidth = -1;
+    int32_t mHeight = -1;
+    Rect mCrop = Rect::INVALID_RECT;
+    Rect mFinalCrop = Rect::INVALID_RECT;
+    float mAlpha = 0.f;
+    uint32_t mFlags = 0;
+    PixelFormat mPixelFormat = PIXEL_FORMAT_NONE;
+    android_dataspace mDataSpace = HAL_DATASPACE_UNKNOWN;
+    // Row-major transform matrix (SurfaceControl::setMatrix())
+    float mMatrix[2][2] = {{0.f, 0.f}, {0.f, 0.f}};
+    int32_t mActiveBufferWidth = -1;
+    int32_t mActiveBufferHeight = -1;
+    int32_t mActiveBufferStride = 0;
+    PixelFormat mActiveBufferFormat = PIXEL_FORMAT_NONE;
+    int32_t mNumQueuedFrames = -1;
+    bool mRefreshPending = false;
+    bool mIsOpaque = false;
+    bool mContentDirty = false;
+};
+
+std::string to_string(const LayerDebugInfo& info);
+
+} // namespace android
diff --git a/libs/gui/include/gui/SurfaceControl.h b/libs/gui/include/gui/SurfaceControl.h
index 8bb705c..c15209d 100644
--- a/libs/gui/include/gui/SurfaceControl.h
+++ b/libs/gui/include/gui/SurfaceControl.h
@@ -90,6 +90,16 @@
     status_t    setFlags(uint32_t flags, uint32_t mask);
     status_t    setTransparentRegionHint(const Region& transparent);
     status_t    setAlpha(float alpha=1.0f);
+
+    // Experimentarily it appears that the matrix transforms the
+    // on-screen rectangle and it's contents before the position is
+    // applied.
+    //
+    // TODO: Test with other combinations to find approximate transformation rules.
+    //
+    // For example:
+    // Layer sized (W,H) set to position (x,y) with matrix M=[-1, 0, 0, 1] (Horizontal flip) gives
+    // [((0, 0), (W, H)) x M] + (x,y) = ((-W, 0), (0, H)) + (x,y) = ((-W + x, y), (x, H+y))
     status_t    setMatrix(float dsdx, float dtdx, float dtdy, float dsdy);
     status_t    setCrop(const Rect& crop);
     status_t    setFinalCrop(const Rect& crop);
diff --git a/libs/gui/tests/Surface_test.cpp b/libs/gui/tests/Surface_test.cpp
index e18af17..45e95a5 100644
--- a/libs/gui/tests/Surface_test.cpp
+++ b/libs/gui/tests/Surface_test.cpp
@@ -539,6 +539,9 @@
         return NO_ERROR;
     }
     status_t injectVSync(nsecs_t /*when*/) override { return NO_ERROR; }
+    status_t getLayerDebugInfo(std::vector<LayerDebugInfo>* /*layers*/) const override {
+        return NO_ERROR;
+    }
 
 protected:
     IBinder* onAsBinder() override { return nullptr; }
diff --git a/libs/input/InputTransport.cpp b/libs/input/InputTransport.cpp
index d5c5927..63e98bb 100644
--- a/libs/input/InputTransport.cpp
+++ b/libs/input/InputTransport.cpp
@@ -450,7 +450,7 @@
             break;
         }
 
-        case AINPUT_EVENT_TYPE_MOTION: {
+        case InputMessage::TYPE_MOTION: {
             ssize_t batchIndex = findBatch(mMsg.body.motion.deviceId, mMsg.body.motion.source);
             if (batchIndex >= 0) {
                 Batch& batch = mBatches.editItemAt(batchIndex);
diff --git a/libs/input/VelocityTracker.cpp b/libs/input/VelocityTracker.cpp
index b174fa8..62acea3 100644
--- a/libs/input/VelocityTracker.cpp
+++ b/libs/input/VelocityTracker.cpp
@@ -556,6 +556,46 @@
     return true;
 }
 
+/*
+ * Optimized unweighted second-order least squares fit. About 2x speed improvement compared to
+ * the default implementation
+ */
+static float solveUnweightedLeastSquaresDeg2(const float* x, const float* y, size_t count) {
+    float sxi = 0, sxiyi = 0, syi = 0, sxi2 = 0, sxi3 = 0, sxi2yi = 0, sxi4 = 0;
+
+    for (size_t i = 0; i < count; i++) {
+        float xi = x[i];
+        float yi = y[i];
+        float xi2 = xi*xi;
+        float xi3 = xi2*xi;
+        float xi4 = xi3*xi;
+        float xi2yi = xi2*yi;
+        float xiyi = xi*yi;
+
+        sxi += xi;
+        sxi2 += xi2;
+        sxiyi += xiyi;
+        sxi2yi += xi2yi;
+        syi += yi;
+        sxi3 += xi3;
+        sxi4 += xi4;
+    }
+
+    float Sxx = sxi2 - sxi*sxi / count;
+    float Sxy = sxiyi - sxi*syi / count;
+    float Sxx2 = sxi3 - sxi*sxi2 / count;
+    float Sx2y = sxi2yi - sxi2*syi / count;
+    float Sx2x2 = sxi4 - sxi2*sxi2 / count;
+
+    float numerator = Sxy*Sx2x2 - Sx2y*Sxx2;
+    float denominator = Sxx*Sx2x2 - Sxx2*Sxx2;
+    if (denominator == 0) {
+        ALOGW("division by 0 when computing velocity, Sxx=%f, Sx2x2=%f, Sxx2=%f", Sxx, Sx2x2, Sxx2);
+        return 0;
+    }
+    return numerator/denominator;
+}
+
 bool LeastSquaresVelocityTrackerStrategy::getEstimator(uint32_t id,
         VelocityTracker::Estimator* outEstimator) const {
     outEstimator->clear();
@@ -597,6 +637,19 @@
         degree = m - 1;
     }
     if (degree >= 1) {
+        if (degree == 2 && mWeighting == WEIGHTING_NONE) { // optimize unweighted, degree=2 fit
+            outEstimator->time = newestMovement.eventTime;
+            outEstimator->degree = 2;
+            outEstimator->confidence = 1;
+            outEstimator->xCoeff[0] = 0; // only slope is calculated, set rest of coefficients = 0
+            outEstimator->yCoeff[0] = 0;
+            outEstimator->xCoeff[1] = solveUnweightedLeastSquaresDeg2(time, x, m);
+            outEstimator->yCoeff[1] = solveUnweightedLeastSquaresDeg2(time, y, m);
+            outEstimator->xCoeff[2] = 0;
+            outEstimator->yCoeff[2] = 0;
+            return true;
+        }
+
         float xdet, ydet;
         uint32_t n = degree + 1;
         if (solveLeastSquares(time, x, w, m, n, outEstimator->xCoeff, &xdet)
diff --git a/libs/ui/DebugUtils.cpp b/libs/ui/DebugUtils.cpp
index d5676cc..2d72944 100644
--- a/libs/ui/DebugUtils.cpp
+++ b/libs/ui/DebugUtils.cpp
@@ -16,10 +16,13 @@
 
 #include <ui/DebugUtils.h>
 #include <ui/PixelFormat.h>
+#include <ui/Rect.h>
 
 #include <android-base/stringprintf.h>
 #include <string>
 
+using android::base::StringPrintf;
+
 std::string decodeStandard(android_dataspace dataspace) {
     const uint32_t dataspaceSelect = (dataspace & HAL_DATASPACE_STANDARD_MASK);
     switch (dataspaceSelect) {
@@ -187,7 +190,7 @@
 
 std::string dataspaceDetails(android_dataspace dataspace) {
     if (dataspace == 0) {
-        return "Default (0)";
+        return "Default";
     }
     return android::base::StringPrintf("%s %s %s", decodeStandard(dataspace).c_str(),
                                        decodeTransfer(dataspace).c_str(),
@@ -262,3 +265,7 @@
             return android::base::StringPrintf("Unknown %#08x", format);
     }
 }
+
+std::string to_string(const android::Rect& rect) {
+    return StringPrintf("(%4d,%4d,%4d,%4d)", rect.left, rect.top, rect.right, rect.bottom);
+}
diff --git a/libs/ui/include/ui/DebugUtils.h b/libs/ui/include/ui/DebugUtils.h
index 30f4a59..dad9446 100644
--- a/libs/ui/include/ui/DebugUtils.h
+++ b/libs/ui/include/ui/DebugUtils.h
@@ -21,9 +21,14 @@
 
 #include <string>
 
+namespace android {
+class Rect;
+}
+
 std::string decodeStandard(android_dataspace dataspace);
 std::string decodeTransfer(android_dataspace dataspace);
 std::string decodeRange(android_dataspace dataspace);
 std::string dataspaceDetails(android_dataspace dataspace);
 std::string decodeColorMode(android_color_mode colormode);
 std::string decodePixelFormat(android::PixelFormat format);
+std::string to_string(const android::Rect& rect);
diff --git a/libs/vr/libvrflinger/hardware_composer.cpp b/libs/vr/libvrflinger/hardware_composer.cpp
index 3418d65..f9a5dcd 100644
--- a/libs/vr/libvrflinger/hardware_composer.cpp
+++ b/libs/vr/libvrflinger/hardware_composer.cpp
@@ -198,7 +198,7 @@
 }
 
 void HardwareComposer::OnPostThreadResumed() {
-  hidl_.reset(new Hwc2::Composer(false));
+  hidl_.reset(new Hwc2::Composer("default"));
   hidl_callback_ = new ComposerCallback;
   hidl_->registerCallback(hidl_callback_);
 
diff --git a/opengl/include/GLES/gl.h b/opengl/include/GLES/gl.h
index 36acff9..25033f2 100644
--- a/opengl/include/GLES/gl.h
+++ b/opengl/include/GLES/gl.h
@@ -51,6 +51,7 @@
 #ifndef GL_VERSION_ES_CM_1_0
 #define GL_VERSION_ES_CM_1_0 1
 typedef void GLvoid;
+typedef char GLchar;
 typedef unsigned int GLenum;
 #include <KHR/khrplatform.h>
 typedef khronos_float_t GLfloat;
diff --git a/opengl/include/GLES/glext.h b/opengl/include/GLES/glext.h
index b6fe620..1a150e3 100644
--- a/opengl/include/GLES/glext.h
+++ b/opengl/include/GLES/glext.h
@@ -104,7 +104,6 @@
 
 #ifndef GL_OES_byte_coordinates
 #define GL_OES_byte_coordinates 1
-typedef khronos_int8_t GLbyte;
 #endif /* GL_OES_byte_coordinates */
 
 #ifndef GL_OES_compressed_ETC1_RGB8_sub_texture
@@ -128,7 +127,6 @@
 
 #ifndef GL_OES_draw_texture
 #define GL_OES_draw_texture 1
-typedef short GLshort;
 #define GL_TEXTURE_CROP_RECT_OES          0x8B9D
 typedef void (GL_APIENTRYP PFNGLDRAWTEXSOESPROC) (GLshort x, GLshort y, GLshort z, GLshort width, GLshort height);
 typedef void (GL_APIENTRYP PFNGLDRAWTEXIOESPROC) (GLint x, GLint y, GLint z, GLint width, GLint height);
@@ -409,7 +407,6 @@
 
 #ifndef GL_OES_single_precision
 #define GL_OES_single_precision 1
-typedef khronos_float_t GLclampf;
 typedef void (GL_APIENTRYP PFNGLCLEARDEPTHFOESPROC) (GLclampf depth);
 typedef void (GL_APIENTRYP PFNGLCLIPPLANEFOESPROC) (GLenum plane, const GLfloat *equation);
 typedef void (GL_APIENTRYP PFNGLDEPTHRANGEFOESPROC) (GLclampf n, GLclampf f);
diff --git a/opengl/tests/hwc/hwcRects.cpp b/opengl/tests/hwc/hwcRects.cpp
index 69e56ff..5956366 100644
--- a/opengl/tests/hwc/hwcRects.cpp
+++ b/opengl/tests/hwc/hwcRects.cpp
@@ -170,7 +170,7 @@
 static EGLint width, height;
 
 // Function prototypes
-static Rectangle parseRect(string rectStr);
+static Rectangle parseRect(const string& rectStr);
 void init(void);
 void printSyntax(const char *cmd);
 
@@ -358,7 +358,7 @@
 
 // Parse string description of rectangle and add it to list of rectangles
 // to be rendered.
-static Rectangle parseRect(string rectStr)
+static Rectangle parseRect(const string& rectStr)
 {
     int rv;
     string str;
diff --git a/services/surfaceflinger/Android.bp b/services/surfaceflinger/Android.bp
index cc93105..4775e4e 100644
--- a/services/surfaceflinger/Android.bp
+++ b/services/surfaceflinger/Android.bp
@@ -2,3 +2,5 @@
     name: "libsurfaceflingerincludes",
     export_include_dirs: ["."],
 }
+
+subdirs = ["tests/fakehwc"]
\ No newline at end of file
diff --git a/services/surfaceflinger/DisplayDevice.cpp b/services/surfaceflinger/DisplayDevice.cpp
index b28c9ba..248ef53 100644
--- a/services/surfaceflinger/DisplayDevice.cpp
+++ b/services/surfaceflinger/DisplayDevice.cpp
@@ -65,7 +65,7 @@
 using namespace android::hardware::configstore::V1_0;
 
 static bool useTripleFramebuffer = getInt64< ISurfaceFlingerConfigs,
-        &ISurfaceFlingerConfigs::maxFrameBufferAcquiredBuffers>(2) == 3;
+        &ISurfaceFlingerConfigs::maxFrameBufferAcquiredBuffers>(2) >= 3;
 
 #if !defined(EGL_EGLEXT_PROTOTYPES) || !defined(EGL_ANDROID_swap_rectangle)
 // Dummy implementation in case it is missing.
diff --git a/services/surfaceflinger/DisplayHardware/ComposerHal.cpp b/services/surfaceflinger/DisplayHardware/ComposerHal.cpp
index ac739a2..433a224 100644
--- a/services/surfaceflinger/DisplayHardware/ComposerHal.cpp
+++ b/services/surfaceflinger/DisplayHardware/ComposerHal.cpp
@@ -157,15 +157,11 @@
     write64(metadata.usage);
 }
 
-Composer::Composer(bool useVrComposer)
+Composer::Composer(const std::string& serviceName)
     : mWriter(kWriterInitialSize),
-      mIsUsingVrComposer(useVrComposer)
+      mIsUsingVrComposer(serviceName == std::string("vr"))
 {
-    if (mIsUsingVrComposer) {
-        mComposer = IComposer::getService("vr");
-    } else {
-        mComposer = IComposer::getService(); // use default name
-    }
+    mComposer = IComposer::getService(serviceName);
 
     if (mComposer == nullptr) {
         LOG_ALWAYS_FATAL("failed to get hwcomposer service");
diff --git a/services/surfaceflinger/DisplayHardware/ComposerHal.h b/services/surfaceflinger/DisplayHardware/ComposerHal.h
index 533509b..31a3c1d 100644
--- a/services/surfaceflinger/DisplayHardware/ComposerHal.h
+++ b/services/surfaceflinger/DisplayHardware/ComposerHal.h
@@ -136,7 +136,7 @@
 // Composer is a wrapper to IComposer, a proxy to server-side composer.
 class Composer {
 public:
-    Composer(bool useVrComposer);
+    Composer(const std::string& serviceName);
 
     std::vector<IComposer::Capability> getCapabilities();
     std::string dumpDebugInfo();
diff --git a/services/surfaceflinger/DisplayHardware/FramebufferSurface.cpp b/services/surfaceflinger/DisplayHardware/FramebufferSurface.cpp
index 1ac21c6..93c6d54 100644
--- a/services/surfaceflinger/DisplayHardware/FramebufferSurface.cpp
+++ b/services/surfaceflinger/DisplayHardware/FramebufferSurface.cpp
@@ -34,6 +34,7 @@
 #include <gui/BufferQueue.h>
 #include <gui/Surface.h>
 
+#include <ui/DebugUtils.h>
 #include <ui/GraphicBuffer.h>
 #include <ui/Rect.h>
 
@@ -103,6 +104,7 @@
     sp<Fence> acquireFence(Fence::NO_FENCE);
     android_dataspace_t dataspace = HAL_DATASPACE_UNKNOWN;
     status_t result = nextBuffer(slot, buf, acquireFence, dataspace);
+    mDataSpace = dataspace;
     if (result != NO_ERROR) {
         ALOGE("error latching next FramebufferSurface buffer: %s (%d)",
                 strerror(-result), result);
@@ -249,7 +251,10 @@
 #endif
 
 void FramebufferSurface::dumpAsString(String8& result) const {
-    ConsumerBase::dumpState(result);
+    Mutex::Autolock lock(mMutex);
+    result.appendFormat("FramebufferSurface: dataspace: %s(%d)\n",
+                        dataspaceDetails(mDataSpace).c_str(), mDataSpace);
+    ConsumerBase::dumpLocked(result, "");
 }
 
 void FramebufferSurface::dumpLocked(String8& result, const char* prefix) const
diff --git a/services/surfaceflinger/DisplayHardware/FramebufferSurface.h b/services/surfaceflinger/DisplayHardware/FramebufferSurface.h
index 69a72d7..a1756ca 100644
--- a/services/surfaceflinger/DisplayHardware/FramebufferSurface.h
+++ b/services/surfaceflinger/DisplayHardware/FramebufferSurface.h
@@ -83,6 +83,13 @@
     // or the buffer is not associated with a slot.
     int mCurrentBufferSlot;
 
+    // mDataSpace is the dataspace of the current composition buffer for
+    // this FramebufferSurface. It will be 0 when HWC is doing the
+    // compositing. Otherwise it will display the dataspace of the buffer
+    // use for compositing which can change as wide-color content is
+    // on/off.
+    android_dataspace mDataSpace;
+
     // mCurrentBuffer is the current buffer or NULL to indicate that there is
     // no current buffer.
     sp<GraphicBuffer> mCurrentBuffer;
diff --git a/services/surfaceflinger/DisplayHardware/HWC2.cpp b/services/surfaceflinger/DisplayHardware/HWC2.cpp
index ae44ae0..78c0c85 100644
--- a/services/surfaceflinger/DisplayHardware/HWC2.cpp
+++ b/services/surfaceflinger/DisplayHardware/HWC2.cpp
@@ -98,8 +98,8 @@
 
 // Device methods
 
-Device::Device(bool useVrComposer)
-  : mComposer(std::make_unique<Hwc2::Composer>(useVrComposer)),
+Device::Device(const std::string& serviceName)
+  : mComposer(std::make_unique<Hwc2::Composer>(serviceName)),
     mCapabilities(),
     mDisplays(),
     mRegisteredCallback(false)
diff --git a/services/surfaceflinger/DisplayHardware/HWC2.h b/services/surfaceflinger/DisplayHardware/HWC2.h
index 949f0e3..fbe4c7e 100644
--- a/services/surfaceflinger/DisplayHardware/HWC2.h
+++ b/services/surfaceflinger/DisplayHardware/HWC2.h
@@ -79,10 +79,9 @@
 class Device
 {
 public:
-    // useVrComposer is passed to the composer HAL. When true, the composer HAL
-    // will use the vr composer service, otherwise it uses the real hardware
-    // composer.
-    Device(bool useVrComposer);
+    // Service name is expected to be 'default' or 'vr' for normal use.
+    // 'vr' will slightly modify the behavior of the mComposer.
+    Device(const std::string& serviceName);
 
     void registerCallback(ComposerCallback* callback, int32_t sequenceId);
 
diff --git a/services/surfaceflinger/DisplayHardware/HWComposer.cpp b/services/surfaceflinger/DisplayHardware/HWComposer.cpp
index 3f3c67b..b096a3a 100644
--- a/services/surfaceflinger/DisplayHardware/HWComposer.cpp
+++ b/services/surfaceflinger/DisplayHardware/HWComposer.cpp
@@ -59,7 +59,7 @@
 
 // ---------------------------------------------------------------------------
 
-HWComposer::HWComposer(bool useVrComposer)
+HWComposer::HWComposer(const std::string& serviceName)
     : mHwcDevice(),
       mDisplayData(2),
       mFreeDisplaySlots(),
@@ -73,7 +73,7 @@
         mVSyncCounts[i] = 0;
     }
 
-    mHwcDevice = std::make_unique<HWC2::Device>(useVrComposer);
+    mHwcDevice = std::make_unique<HWC2::Device>(serviceName);
     mRemainingHwcVirtualDisplays = mHwcDevice->getMaxVirtualDisplayCount();
 }
 
diff --git a/services/surfaceflinger/DisplayHardware/HWComposer.h b/services/surfaceflinger/DisplayHardware/HWComposer.h
index e25dee1..3640bb5 100644
--- a/services/surfaceflinger/DisplayHardware/HWComposer.h
+++ b/services/surfaceflinger/DisplayHardware/HWComposer.h
@@ -65,10 +65,9 @@
 class HWComposer
 {
 public:
-    // useVrComposer is passed to the composer HAL. When true, the composer HAL
-    // will use the vr composer service, otherwise it uses the real hardware
-    // composer.
-    HWComposer(bool useVrComposer);
+    // Uses the named composer service. Valid choices for normal use
+    // are 'default' and 'vr'.
+    HWComposer(const std::string& serviceName);
 
     ~HWComposer();
 
diff --git a/services/surfaceflinger/Layer.cpp b/services/surfaceflinger/Layer.cpp
index 4edde14..54d4cbd 100755
--- a/services/surfaceflinger/Layer.cpp
+++ b/services/surfaceflinger/Layer.cpp
@@ -40,6 +40,7 @@
 
 #include <gui/BufferItem.h>
 #include <gui/BufferQueue.h>
+#include <gui/LayerDebugInfo.h>
 #include <gui/Surface.h>
 
 #include "clz.h"
@@ -2411,69 +2412,51 @@
 // debugging
 // ----------------------------------------------------------------------------
 
-void Layer::dump(String8& result, Colorizer& colorizer) const
-{
-    const Layer::State& s(getDrawingState());
-
-    colorizer.colorize(result, Colorizer::GREEN);
-    result.appendFormat(
-            "+ %s %p (%s)\n",
-            getTypeId(), this, getName().string());
-    colorizer.reset(result);
-
-    s.activeTransparentRegion.dump(result, "transparentRegion");
-    visibleRegion.dump(result, "visibleRegion");
-    surfaceDamageRegion.dump(result, "surfaceDamageRegion");
-    sp<Client> client(mClientRef.promote());
-    PixelFormat pf = PIXEL_FORMAT_UNKNOWN;
-    const sp<GraphicBuffer>& buffer(getActiveBuffer());
-    if (buffer != NULL) {
-        pf = buffer->getPixelFormat();
+LayerDebugInfo Layer::getLayerDebugInfo() const {
+    LayerDebugInfo info;
+    const Layer::State& ds = getDrawingState();
+    info.mName = getName();
+    sp<Layer> parent = getParent();
+    info.mParentName = (parent == nullptr ? std::string("none") : parent->getName().string());
+    info.mType = String8(getTypeId());
+    info.mTransparentRegion = ds.activeTransparentRegion;
+    info.mVisibleRegion = visibleRegion;
+    info.mSurfaceDamageRegion = surfaceDamageRegion;
+    info.mLayerStack = getLayerStack();
+    info.mX = ds.active.transform.tx();
+    info.mY = ds.active.transform.ty();
+    info.mZ = ds.z;
+    info.mWidth = ds.active.w;
+    info.mHeight = ds.active.h;
+    info.mCrop = ds.crop;
+    info.mFinalCrop = ds.finalCrop;
+    info.mAlpha = ds.alpha;
+    info.mFlags = ds.flags;
+    info.mPixelFormat = getPixelFormat();
+    info.mDataSpace = getDataSpace();
+    info.mMatrix[0][0] = ds.active.transform[0][0];
+    info.mMatrix[0][1] = ds.active.transform[0][1];
+    info.mMatrix[1][0] = ds.active.transform[1][0];
+    info.mMatrix[1][1] = ds.active.transform[1][1];
+    {
+        sp<const GraphicBuffer> activeBuffer = getActiveBuffer();
+        if (activeBuffer != 0) {
+            info.mActiveBufferWidth = activeBuffer->getWidth();
+            info.mActiveBufferHeight = activeBuffer->getHeight();
+            info.mActiveBufferStride = activeBuffer->getStride();
+            info.mActiveBufferFormat = activeBuffer->format;
+        } else {
+            info.mActiveBufferWidth = 0;
+            info.mActiveBufferHeight = 0;
+            info.mActiveBufferStride = 0;
+            info.mActiveBufferFormat = 0;
+        }
     }
-
-    result.appendFormat(            "      "
-            "layerStack=%4d, z=%9d, pos=(%g,%g), size=(%4d,%4d), "
-            "crop=(%4d,%4d,%4d,%4d), finalCrop=(%4d,%4d,%4d,%4d), "
-            "isOpaque=%1d, invalidate=%1d, "
-            "dataspace=%s, pixelformat=%s "
-#ifdef USE_HWC2
-            "alpha=%.3f, flags=0x%08x, tr=[%.2f, %.2f][%.2f, %.2f]\n"
-#else
-            "alpha=0x%02x, flags=0x%08x, tr=[%.2f, %.2f][%.2f, %.2f]\n"
-#endif
-            "      client=%p\n",
-            getLayerStack(), s.z,
-            s.active.transform.tx(), s.active.transform.ty(),
-            s.active.w, s.active.h,
-            s.crop.left, s.crop.top,
-            s.crop.right, s.crop.bottom,
-            s.finalCrop.left, s.finalCrop.top,
-            s.finalCrop.right, s.finalCrop.bottom,
-            isOpaque(s), contentDirty,
-            dataspaceDetails(getDataSpace()).c_str(), decodePixelFormat(pf).c_str(),
-            s.alpha, s.flags,
-            s.active.transform[0][0], s.active.transform[0][1],
-            s.active.transform[1][0], s.active.transform[1][1],
-            client.get());
-
-    sp<const GraphicBuffer> buf0(mActiveBuffer);
-    uint32_t w0=0, h0=0, s0=0, f0=0;
-    if (buf0 != 0) {
-        w0 = buf0->getWidth();
-        h0 = buf0->getHeight();
-        s0 = buf0->getStride();
-        f0 = buf0->format;
-    }
-    result.appendFormat(
-            "      "
-            "format=%2d, activeBuffer=[%4ux%4u:%4u,%3X],"
-            " queued-frames=%d, mRefreshPending=%d\n",
-            mFormat, w0, h0, s0,f0,
-            mQueuedFrames, mRefreshPending);
-
-    if (mSurfaceFlingerConsumer != 0) {
-        mSurfaceFlingerConsumer->dumpState(result, "            ");
-    }
+    info.mNumQueuedFrames = getQueuedFrameCount();
+    info.mRefreshPending = isBufferLatched();
+    info.mIsOpaque = isOpaque(ds);
+    info.mContentDirty = contentDirty;
+    return info;
 }
 
 #ifdef USE_HWC2
diff --git a/services/surfaceflinger/Layer.h b/services/surfaceflinger/Layer.h
index 222718b..1b7d075 100644
--- a/services/surfaceflinger/Layer.h
+++ b/services/surfaceflinger/Layer.h
@@ -60,6 +60,7 @@
 class DisplayDevice;
 class GraphicBuffer;
 class SurfaceFlinger;
+class LayerDebugInfo;
 
 // ---------------------------------------------------------------------------
 
@@ -441,6 +442,8 @@
     bool hasQueuedFrame() const { return mQueuedFrames > 0 ||
             mSidebandStreamChanged || mAutoRefresh; }
 
+    int32_t getQueuedFrameCount() const { return mQueuedFrames; }
+
 #ifdef USE_HWC2
     // -----------------------------------------------------------------------
 
@@ -473,9 +476,9 @@
     inline  const State&    getCurrentState() const { return mCurrentState; }
     inline  State&          getCurrentState()       { return mCurrentState; }
 
+    LayerDebugInfo getLayerDebugInfo() const;
 
     /* always call base class first */
-    void dump(String8& result, Colorizer& colorizer) const;
 #ifdef USE_HWC2
     static void miniDumpHeader(String8& result);
     void miniDump(String8& result, int32_t hwcId) const;
@@ -673,6 +676,9 @@
     sp<IGraphicBufferProducer> getProducer() const;
     const String8& getName() const;
     void notifyAvailableFrames();
+
+    PixelFormat getPixelFormat() const { return mFormat; }
+
 private:
 
     // -----------------------------------------------------------------------
diff --git a/services/surfaceflinger/SurfaceFlinger.cpp b/services/surfaceflinger/SurfaceFlinger.cpp
index 06e2a7f..9ee88aa 100644
--- a/services/surfaceflinger/SurfaceFlinger.cpp
+++ b/services/surfaceflinger/SurfaceFlinger.cpp
@@ -46,6 +46,7 @@
 #include <gui/BufferQueue.h>
 #include <gui/GuiConfig.h>
 #include <gui/IDisplayEventConnection.h>
+#include <gui/LayerDebugInfo.h>
 #include <gui/Surface.h>
 
 #include <ui/GraphicBufferAllocator.h>
@@ -138,6 +139,21 @@
 int64_t SurfaceFlinger::maxFrameBufferAcquiredBuffers;
 bool SurfaceFlinger::hasWideColorDisplay;
 
+
+std::string getHwcServiceName() {
+    char value[PROPERTY_VALUE_MAX] = {};
+    property_get("debug.sf.hwc_service_name", value, "default");
+    ALOGI("Using HWComposer service: '%s'", value);
+    return std::string(value);
+}
+
+bool useTrebleTestingOverride() {
+    char value[PROPERTY_VALUE_MAX] = {};
+    property_get("debug.sf.treble_testing_override", value, "false");
+    ALOGI("Treble testing override: '%s'", value);
+    return std::string(value) == "true";
+}
+
 SurfaceFlinger::SurfaceFlinger()
     :   BnSurfaceComposer(),
         mTransactionFlags(0),
@@ -146,6 +162,7 @@
         mLayersRemoved(false),
         mLayersAdded(false),
         mRepaintEverything(0),
+        mHwcServiceName(getHwcServiceName()),
         mRenderEngine(nullptr),
         mBootTime(systemTime()),
         mBuiltinDisplays(),
@@ -247,6 +264,15 @@
     // but since /data may be encrypted, we need to wait until after vold
     // comes online to attempt to read the property. The property is
     // instead read after the boot animation
+
+    if (useTrebleTestingOverride()) {
+        // Without the override SurfaceFlinger cannot connect to HIDL
+        // services that are not listed in the manifests.  Considered
+        // deriving the setting from the set service name, but it
+        // would be brittle if the name that's not 'default' is used
+        // for production purposes later on.
+        setenv("TREBLE_TESTING_OVERRIDE", "true", true);
+    }
 }
 
 void SurfaceFlinger::onFirstRef()
@@ -609,7 +635,7 @@
 
     LOG_ALWAYS_FATAL_IF(mVrFlingerRequestsDisplay,
             "Starting with vr flinger active is not currently supported.");
-    mHwc.reset(new HWComposer(false));
+    mHwc.reset(new HWComposer(mHwcServiceName));
     mHwc->registerCallback(this, mComposerSequenceId);
 
     if (useVrFlinger) {
@@ -1057,6 +1083,33 @@
     return NO_ERROR;
 }
 
+status_t SurfaceFlinger::getLayerDebugInfo(std::vector<LayerDebugInfo>* outLayers) const {
+    IPCThreadState* ipc = IPCThreadState::self();
+    const int pid = ipc->getCallingPid();
+    const int uid = ipc->getCallingUid();
+    if ((uid != AID_SHELL) &&
+            !PermissionCache::checkPermission(sDump, pid, uid)) {
+        ALOGE("Layer debug info permission denied for pid=%d, uid=%d", pid, uid);
+        return PERMISSION_DENIED;
+    }
+
+    // Try to acquire a lock for 1s, fail gracefully
+    const status_t err = mStateLock.timedLock(s2ns(1));
+    const bool locked = (err == NO_ERROR);
+    if (!locked) {
+        ALOGE("LayerDebugInfo: SurfaceFlinger unresponsive (%s [%d]) - exit", strerror(-err), err);
+        return TIMED_OUT;
+    }
+
+    outLayers->clear();
+    mCurrentState.traverseInZOrder([&](Layer* layer) {
+        outLayers->push_back(layer->getLayerDebugInfo());
+    });
+
+    mStateLock.unlock();
+    return NO_ERROR;
+}
+
 // ----------------------------------------------------------------------------
 
 sp<IDisplayEventConnection> SurfaceFlinger::createDisplayEventConnection(
@@ -1342,7 +1395,8 @@
 
     resetDisplayState();
     mHwc.reset();  // Delete the current instance before creating the new one
-    mHwc.reset(new HWComposer(vrFlingerRequestsDisplay));
+    mHwc.reset(new HWComposer(
+            vrFlingerRequestsDisplay ? "vr" : mHwcServiceName));
     mHwc->registerCallback(this, ++mComposerSequenceId);
 
     LOG_ALWAYS_FATAL_IF(!mHwc->getComposer()->isRemote(),
@@ -2987,7 +3041,10 @@
             }
         }
         if (what & layer_state_t::eRelativeLayerChanged) {
+            ssize_t idx = mCurrentState.layersSortedByZ.indexOf(layer);
             if (layer->setRelativeLayer(s.relativeLayerHandle, s.z)) {
+                mCurrentState.layersSortedByZ.removeAt(idx);
+                mCurrentState.layersSortedByZ.add(layer);
                 flags |= eTransactionNeeded|eTraversalNeeded;
             }
         }
@@ -3712,7 +3769,7 @@
     result.appendFormat("Visible layers (count = %zu)\n", mNumLayers);
     colorizer.reset(result);
     mCurrentState.traverseInZOrder([&](Layer* layer) {
-        layer->dump(result, colorizer);
+        result.append(to_string(layer->getLayerDebugInfo()).c_str());
     });
 
     /*
diff --git a/services/surfaceflinger/SurfaceFlinger.h b/services/surfaceflinger/SurfaceFlinger.h
index 025da0e..058f4a1 100644
--- a/services/surfaceflinger/SurfaceFlinger.h
+++ b/services/surfaceflinger/SurfaceFlinger.h
@@ -311,6 +311,7 @@
             HdrCapabilities* outCapabilities) const;
     virtual status_t enableVSyncInjections(bool enable);
     virtual status_t injectVSync(nsecs_t when);
+    virtual status_t getLayerDebugInfo(std::vector<LayerDebugInfo>* outLayers) const;
 
 
     /* ------------------------------------------------------------------------
@@ -646,6 +647,10 @@
     // vr, our HWComposer instance will be recreated.
     std::unique_ptr<HWComposer> mHwc;
 
+#ifdef USE_HWC2
+    const std::string mHwcServiceName; // "default" for real use, something else for testing.
+#endif
+
     // constant members (no synchronization needed for access)
     RenderEngine* mRenderEngine;
     nsecs_t mBootTime;
diff --git a/services/surfaceflinger/SurfaceFlinger_hwc1.cpp b/services/surfaceflinger/SurfaceFlinger_hwc1.cpp
index a41d35f..78a04e0 100644
--- a/services/surfaceflinger/SurfaceFlinger_hwc1.cpp
+++ b/services/surfaceflinger/SurfaceFlinger_hwc1.cpp
@@ -41,6 +41,7 @@
 #include <gui/BufferQueue.h>
 #include <gui/GuiConfig.h>
 #include <gui/IDisplayEventConnection.h>
+#include <gui/LayerDebugInfo.h>
 #include <gui/Surface.h>
 
 #include <ui/GraphicBufferAllocator.h>
@@ -931,6 +932,34 @@
     return NO_ERROR;
 }
 
+status_t SurfaceFlinger::getLayerDebugInfo(std::vector<LayerDebugInfo>* outLayers) const {
+    IPCThreadState* ipc = IPCThreadState::self();
+    const int pid = ipc->getCallingPid();
+    const int uid = ipc->getCallingUid();
+    if ((uid != AID_SHELL) &&
+            !PermissionCache::checkPermission(sDump, pid, uid)) {
+        ALOGE("Layer debug info permission denied for pid=%d, uid=%d", pid, uid);
+        return PERMISSION_DENIED;
+    }
+
+    // Try to acquire a lock for 1s, fail gracefully
+    status_t err = mStateLock.timedLock(s2ns(1));
+    bool locked = (err == NO_ERROR);
+    if (!locked) {
+        ALOGE("LayerDebugInfo: SurfaceFlinger unresponsive (%s [%d]) - exit", strerror(-err), err);
+        return TIMED_OUT;
+    }
+
+    outLayers->clear();
+    mCurrentState.traverseInZOrder([&](Layer* layer) {
+            outLayers->push_back(layer->getLayerDebugInfo());
+        });
+
+    mStateLock.unlock();
+
+    return NO_ERROR;
+}
+
 // ----------------------------------------------------------------------------
 
 sp<IDisplayEventConnection> SurfaceFlinger::createDisplayEventConnection(
@@ -2576,6 +2605,14 @@
                 }
             }
         }
+        if (what & layer_state_t::eRelativeLayerChanged) {
+            ssize_t idx = mCurrentState.layersSortedByZ.indexOf(layer);
+            if (layer->setRelativeLayer(s.relativeLayerHandle, s.z)) {
+                mCurrentState.layersSortedByZ.removeAt(idx);
+                mCurrentState.layersSortedByZ.add(layer);
+                flags |= eTransactionNeeded|eTraversalNeeded;
+            }
+        }
         if (what & layer_state_t::eSizeChanged) {
             if (layer->setSize(s.w, s.h)) {
                 flags |= eTraversalNeeded;
@@ -3253,7 +3290,7 @@
     result.appendFormat("Visible layers (count = %zu)\n", mNumLayers);
     colorizer.reset(result);
     mCurrentState.traverseInZOrder([&](Layer* layer) {
-        layer->dump(result, colorizer);
+        result.append(to_string(layer->getLayerDebugInfo()).c_str());
     });
 
     /*
diff --git a/services/surfaceflinger/tests/fakehwc/Android.bp b/services/surfaceflinger/tests/fakehwc/Android.bp
new file mode 100644
index 0000000..94f3f25
--- /dev/null
+++ b/services/surfaceflinger/tests/fakehwc/Android.bp
@@ -0,0 +1,35 @@
+cc_test {
+    name: "sffakehwc_test",
+    srcs: [
+         "FakeComposerClient.cpp",
+         "FakeComposerService.cpp",
+         "FakeComposerUtils.cpp",
+         "SFFakeHwc_test.cpp"
+    ],
+    shared_libs: [
+        "libcutils",
+        "libutils",
+        "libbinder",
+        "libui",
+        "libgui",
+        "liblog",
+        "libnativewindow",
+        "android.hardware.graphics.composer@2.1",
+        "android.hardware.graphics.mapper@2.0",
+        "libhwbinder",
+        "libhardware",
+        "libhidlbase",
+        "libsync",
+        "libfmq",
+        "libbase",
+        "libhidltransport"
+    ],
+    static_libs: [
+        "libhwcomposer-client",
+        "libsurfaceflingerincludes",
+        "libtrace_proto",
+        "libgmock"
+    ],
+    tags: ["tests"],
+    test_suites: ["device-tests"]
+}
\ No newline at end of file
diff --git a/services/surfaceflinger/tests/fakehwc/FakeComposerClient.cpp b/services/surfaceflinger/tests/fakehwc/FakeComposerClient.cpp
new file mode 100644
index 0000000..60916f3
--- /dev/null
+++ b/services/surfaceflinger/tests/fakehwc/FakeComposerClient.cpp
@@ -0,0 +1,613 @@
+/*
+ * Copyright (C) 2017 The Android Open Source Project
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *      http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+//#define LOG_NDEBUG 0
+#undef LOG_TAG
+#define LOG_TAG "FakeComposer"
+
+#include "FakeComposerClient.h"
+
+#include <gui/SurfaceComposerClient.h>
+
+#include <log/log.h>
+
+#include <gtest/gtest.h>
+
+#include <inttypes.h>
+#include <time.h>
+#include <algorithm>
+#include <condition_variable>
+#include <iostream>
+#include <mutex>
+#include <set>
+#include <thread>
+
+constexpr Config NULL_DISPLAY_CONFIG = static_cast<Config>(0);
+constexpr Display DEFAULT_DISPLAY = static_cast<Display>(1);
+
+using namespace sftest;
+
+using android::Condition;
+using android::Mutex;
+
+using Clock = std::chrono::steady_clock;
+using TimePoint = std::chrono::time_point<Clock>;
+
+namespace {
+
+// Internal state of a layer in the HWC API.
+class LayerImpl {
+public:
+    LayerImpl() = default;
+
+    bool mValid = true;
+    RenderState mRenderState;
+    uint32_t mZ = 0;
+};
+
+// Struct for storing per frame rectangle state. Contains the render
+// state shared to the test case. Basically a snapshot and a subset of
+// LayerImpl sufficient to re-create the pixels of a layer for the
+// frame.
+struct FrameRect {
+public:
+    FrameRect(Layer layer_, const RenderState& state, uint32_t z_)
+          : layer(layer_), renderState(state), z(z_) {}
+
+    const Layer layer;
+    const RenderState renderState;
+    const uint32_t z;
+};
+
+// Collection of FrameRects forming one rendered frame. Could store
+// related fences and other data in the future.
+class Frame {
+public:
+    Frame() = default;
+    std::vector<std::unique_ptr<FrameRect>> rectangles;
+};
+
+class DelayedEventGenerator {
+public:
+    DelayedEventGenerator(std::function<void()> onTimerExpired)
+          : mOnTimerExpired(onTimerExpired), mThread([this]() { loop(); }) {}
+
+    ~DelayedEventGenerator() {
+        ALOGI("DelayedEventGenerator exiting.");
+        {
+            std::unique_lock<std::mutex> lock(mMutex);
+            mRunning = false;
+            mWakeups.clear();
+            mCondition.notify_one();
+        }
+        mThread.join();
+        ALOGI("DelayedEventGenerator exited.");
+    }
+
+    void wakeAfter(std::chrono::nanoseconds waitTime) {
+        std::unique_lock<std::mutex> lock(mMutex);
+        mWakeups.insert(Clock::now() + waitTime);
+        mCondition.notify_one();
+    }
+
+private:
+    void loop() {
+        while (true) {
+            // Lock scope
+            {
+                std::unique_lock<std::mutex> lock(mMutex);
+                mCondition.wait(lock, [this]() { return !mRunning || !mWakeups.empty(); });
+                if (!mRunning && mWakeups.empty()) {
+                    // This thread should only exit once the destructor has been called and all
+                    // wakeups have been processed
+                    return;
+                }
+
+                // At this point, mWakeups will not be empty
+
+                TimePoint target = *(mWakeups.begin());
+                auto status = mCondition.wait_until(lock, target);
+                while (status == std::cv_status::no_timeout) {
+                    // This was either a spurious wakeup or another wakeup was added, so grab the
+                    // oldest point and wait again
+                    target = *(mWakeups.begin());
+                    status = mCondition.wait_until(lock, target);
+                }
+
+                // status must have been timeout, so we can finally clear this point
+                mWakeups.erase(target);
+            }
+            // Callback *without* locks!
+            mOnTimerExpired();
+        }
+    }
+
+    std::function<void()> mOnTimerExpired;
+    std::thread mThread;
+    std::mutex mMutex;
+    std::condition_variable mCondition;
+    bool mRunning = true;
+    std::set<TimePoint> mWakeups;
+};
+
+} // namespace
+
+FakeComposerClient::FakeComposerClient()
+      : mCallbacksOn(false),
+        mClient(nullptr),
+        mCurrentConfig(NULL_DISPLAY_CONFIG),
+        mVsyncEnabled(false),
+        mLayers(),
+        mDelayedEventGenerator(
+                std::make_unique<DelayedEventGenerator>([this]() { this->requestVSync(); })),
+        mSurfaceComposer(nullptr) {}
+
+FakeComposerClient::~FakeComposerClient() {}
+
+void FakeComposerClient::removeClient() {
+    ALOGV("removeClient");
+    // TODO: Ahooga! Only thing current lifetime management choices in
+    // APIs make possible. Sad.
+    delete this;
+}
+
+void FakeComposerClient::enableCallback(bool enable) {
+    ALOGV("enableCallback");
+    mCallbacksOn = enable;
+    if (mCallbacksOn) {
+        mClient->onHotplug(DEFAULT_DISPLAY, IComposerCallback::Connection::CONNECTED);
+    }
+}
+
+void FakeComposerClient::hotplugDisplay(Display display, IComposerCallback::Connection state) {
+    if (mCallbacksOn) {
+        mClient->onHotplug(display, state);
+    }
+}
+
+uint32_t FakeComposerClient::getMaxVirtualDisplayCount() {
+    ALOGV("getMaxVirtualDisplayCount");
+    return 1;
+}
+
+Error FakeComposerClient::createVirtualDisplay(uint32_t /*width*/, uint32_t /*height*/,
+                                               PixelFormat* /*format*/, Display* /*outDisplay*/) {
+    ALOGV("createVirtualDisplay");
+    return Error::NONE;
+}
+
+Error FakeComposerClient::destroyVirtualDisplay(Display /*display*/) {
+    ALOGV("destroyVirtualDisplay");
+    return Error::NONE;
+}
+
+Error FakeComposerClient::createLayer(Display /*display*/, Layer* outLayer) {
+    ALOGV("createLayer");
+    *outLayer = mLayers.size();
+    auto newLayer = std::make_unique<LayerImpl>();
+    mLayers.push_back(std::move(newLayer));
+    return Error::NONE;
+}
+
+Error FakeComposerClient::destroyLayer(Display /*display*/, Layer layer) {
+    ALOGV("destroyLayer");
+    mLayers[layer]->mValid = false;
+    return Error::NONE;
+}
+
+Error FakeComposerClient::getActiveConfig(Display /*display*/, Config* outConfig) {
+    ALOGV("getActiveConfig");
+
+    // TODO Assert outConfig != nullptr
+
+    // TODO This is my reading of the
+    // IComposerClient::getActiveConfig, but returning BAD_CONFIG
+    // seems to not fit SurfaceFlinger plans. See version 2 below.
+    // if (mCurrentConfig == NULL_DISPLAY_CONFIG) {
+    //     return Error::BAD_CONFIG;
+    // }
+    //*outConfig = mCurrentConfig;
+    *outConfig = 1; // Very special config for you my friend
+    return Error::NONE;
+}
+
+Error FakeComposerClient::getClientTargetSupport(Display /*display*/, uint32_t /*width*/,
+                                                 uint32_t /*height*/, PixelFormat /*format*/,
+                                                 Dataspace /*dataspace*/) {
+    ALOGV("getClientTargetSupport");
+    return Error::NONE;
+}
+
+Error FakeComposerClient::getColorModes(Display /*display*/, hidl_vec<ColorMode>* /*outModes*/) {
+    ALOGV("getColorModes");
+    return Error::NONE;
+}
+
+Error FakeComposerClient::getDisplayAttribute(Display display, Config config,
+                                              IComposerClient::Attribute attribute,
+                                              int32_t* outValue) {
+    ALOGV("getDisplayAttribute (%d, %d, %d, %p)", static_cast<int>(display),
+          static_cast<int>(config), static_cast<int>(attribute), outValue);
+
+    // TODO: SOOO much fun to be had with these alone
+    switch (attribute) {
+        case IComposerClient::Attribute::WIDTH:
+            *outValue = 1920;
+            break;
+        case IComposerClient::Attribute::HEIGHT:
+            *outValue = 1080;
+            break;
+        case IComposerClient::Attribute::VSYNC_PERIOD:
+            *outValue = 1666666666;
+            break; // TOOD: Tests break down if lowered to 16ms?
+        case IComposerClient::Attribute::DPI_X:
+            *outValue = 240;
+            break;
+        case IComposerClient::Attribute::DPI_Y:
+            *outValue = 240;
+            break;
+        default:
+            LOG_ALWAYS_FATAL("Say what!?! New attribute");
+    }
+
+    return Error::NONE;
+}
+
+Error FakeComposerClient::getDisplayConfigs(Display /*display*/, hidl_vec<Config>* outConfigs) {
+    ALOGV("getDisplayConfigs");
+    // TODO assert display == 1, outConfigs != nullptr
+
+    outConfigs->resize(1);
+    (*outConfigs)[0] = 1;
+
+    return Error::NONE;
+}
+
+Error FakeComposerClient::getDisplayName(Display /*display*/, hidl_string* /*outName*/) {
+    ALOGV("getDisplayName");
+    return Error::NONE;
+}
+
+Error FakeComposerClient::getDisplayType(Display /*display*/,
+                                         IComposerClient::DisplayType* outType) {
+    ALOGV("getDisplayType");
+    // TODO: This setting nothing on the output had no effect on initial trials. Is first display
+    // assumed to be physical?
+    *outType = static_cast<IComposerClient::DisplayType>(HWC2_DISPLAY_TYPE_PHYSICAL);
+    return Error::NONE;
+}
+
+Error FakeComposerClient::getDozeSupport(Display /*display*/, bool* /*outSupport*/) {
+    ALOGV("getDozeSupport");
+    return Error::NONE;
+}
+
+Error FakeComposerClient::getHdrCapabilities(Display /*display*/, hidl_vec<Hdr>* /*outTypes*/,
+                                             float* /*outMaxLuminance*/,
+                                             float* /*outMaxAverageLuminance*/,
+                                             float* /*outMinLuminance*/) {
+    ALOGV("getHdrCapabilities");
+    return Error::NONE;
+}
+
+Error FakeComposerClient::setActiveConfig(Display /*display*/, Config config) {
+    ALOGV("setActiveConfig");
+    mCurrentConfig = config;
+    return Error::NONE;
+}
+
+Error FakeComposerClient::setColorMode(Display /*display*/, ColorMode /*mode*/) {
+    ALOGV("setColorMode");
+    return Error::NONE;
+}
+
+Error FakeComposerClient::setPowerMode(Display /*display*/, IComposerClient::PowerMode /*mode*/) {
+    ALOGV("setPowerMode");
+    return Error::NONE;
+}
+
+Error FakeComposerClient::setVsyncEnabled(Display /*display*/, IComposerClient::Vsync enabled) {
+    mVsyncEnabled = (enabled == IComposerClient::Vsync::ENABLE);
+    ALOGV("setVsyncEnabled(%s)", mVsyncEnabled ? "ENABLE" : "DISABLE");
+    return Error::NONE;
+}
+
+Error FakeComposerClient::setColorTransform(Display /*display*/, const float* /*matrix*/,
+                                            int32_t /*hint*/) {
+    ALOGV("setColorTransform");
+    return Error::NONE;
+}
+
+Error FakeComposerClient::setClientTarget(Display /*display*/, buffer_handle_t /*target*/,
+                                          int32_t /*acquireFence*/, int32_t /*dataspace*/,
+                                          const std::vector<hwc_rect_t>& /*damage*/) {
+    ALOGV("setClientTarget");
+    return Error::NONE;
+}
+
+Error FakeComposerClient::setOutputBuffer(Display /*display*/, buffer_handle_t /*buffer*/,
+                                          int32_t /*releaseFence*/) {
+    ALOGV("setOutputBuffer");
+    return Error::NONE;
+}
+
+Error FakeComposerClient::validateDisplay(
+        Display /*display*/, std::vector<Layer>* /*outChangedLayers*/,
+        std::vector<IComposerClient::Composition>* /*outCompositionTypes*/,
+        uint32_t* /*outDisplayRequestMask*/, std::vector<Layer>* /*outRequestedLayers*/,
+        std::vector<uint32_t>* /*outRequestMasks*/) {
+    ALOGV("validateDisplay");
+    // TODO: Assume touching nothing means All Korrekt!
+    return Error::NONE;
+}
+
+Error FakeComposerClient::acceptDisplayChanges(Display /*display*/) {
+    ALOGV("acceptDisplayChanges");
+    // Didn't ask for changes because software is omnipotent.
+    return Error::NONE;
+}
+
+bool layerZOrdering(const std::unique_ptr<FrameRect>& a, const std::unique_ptr<FrameRect>& b) {
+    return a->z <= b->z;
+}
+
+Error FakeComposerClient::presentDisplay(Display /*display*/, int32_t* /*outPresentFence*/,
+                                         std::vector<Layer>* /*outLayers*/,
+                                         std::vector<int32_t>* /*outReleaseFences*/) {
+    ALOGV("presentDisplay");
+    // TODO Leaving layers and their fences out for now. Doing so
+    // means that we've already processed everything. Important to
+    // test that the fences are respected, though. (How?)
+
+    std::unique_ptr<Frame> newFrame(new Frame);
+    for (uint64_t layer = 0; layer < mLayers.size(); layer++) {
+        const LayerImpl& layerImpl = *mLayers[layer];
+
+        if (!layerImpl.mValid) continue;
+
+        auto rect = std::make_unique<FrameRect>(layer, layerImpl.mRenderState, layerImpl.mZ);
+        newFrame->rectangles.push_back(std::move(rect));
+    }
+    std::sort(newFrame->rectangles.begin(), newFrame->rectangles.end(), layerZOrdering);
+    {
+        Mutex::Autolock _l(mStateMutex);
+        mFrames.push_back(std::move(newFrame));
+        mFramesAvailable.broadcast();
+    }
+    return Error::NONE;
+}
+
+Error FakeComposerClient::setLayerCursorPosition(Display /*display*/, Layer /*layer*/,
+                                                 int32_t /*x*/, int32_t /*y*/) {
+    ALOGV("setLayerCursorPosition");
+    return Error::NONE;
+}
+
+Error FakeComposerClient::setLayerBuffer(Display /*display*/, Layer layer, buffer_handle_t buffer,
+                                         int32_t acquireFence) {
+    ALOGV("setLayerBuffer");
+    LayerImpl& l = getLayerImpl(layer);
+    if (buffer != l.mRenderState.mBuffer) {
+        l.mRenderState.mSwapCount++; // TODO: Is setting to same value a swap or not?
+    }
+    l.mRenderState.mBuffer = buffer;
+    l.mRenderState.mAcquireFence = acquireFence;
+
+    return Error::NONE;
+}
+
+Error FakeComposerClient::setLayerSurfaceDamage(Display /*display*/, Layer /*layer*/,
+                                                const std::vector<hwc_rect_t>& /*damage*/) {
+    ALOGV("setLayerSurfaceDamage");
+    return Error::NONE;
+}
+
+Error FakeComposerClient::setLayerBlendMode(Display /*display*/, Layer layer, int32_t mode) {
+    ALOGV("setLayerBlendMode");
+    getLayerImpl(layer).mRenderState.mBlendMode = static_cast<hwc2_blend_mode_t>(mode);
+    return Error::NONE;
+}
+
+Error FakeComposerClient::setLayerColor(Display /*display*/, Layer layer,
+                                        IComposerClient::Color color) {
+    ALOGV("setLayerColor");
+    getLayerImpl(layer).mRenderState.mLayerColor.r = color.r;
+    getLayerImpl(layer).mRenderState.mLayerColor.g = color.g;
+    getLayerImpl(layer).mRenderState.mLayerColor.b = color.b;
+    getLayerImpl(layer).mRenderState.mLayerColor.a = color.a;
+    return Error::NONE;
+}
+
+Error FakeComposerClient::setLayerCompositionType(Display /*display*/, Layer /*layer*/,
+                                                  int32_t /*type*/) {
+    ALOGV("setLayerCompositionType");
+    return Error::NONE;
+}
+
+Error FakeComposerClient::setLayerDataspace(Display /*display*/, Layer /*layer*/,
+                                            int32_t /*dataspace*/) {
+    ALOGV("setLayerDataspace");
+    return Error::NONE;
+}
+
+Error FakeComposerClient::setLayerDisplayFrame(Display /*display*/, Layer layer,
+                                               const hwc_rect_t& frame) {
+    ALOGV("setLayerDisplayFrame (%d, %d, %d, %d)", frame.left, frame.top, frame.right,
+          frame.bottom);
+    getLayerImpl(layer).mRenderState.mDisplayFrame = frame;
+    return Error::NONE;
+}
+
+Error FakeComposerClient::setLayerPlaneAlpha(Display /*display*/, Layer layer, float alpha) {
+    ALOGV("setLayerPlaneAlpha");
+    getLayerImpl(layer).mRenderState.mPlaneAlpha = alpha;
+    return Error::NONE;
+}
+
+Error FakeComposerClient::setLayerSidebandStream(Display /*display*/, Layer /*layer*/,
+                                                 buffer_handle_t /*stream*/) {
+    ALOGV("setLayerSidebandStream");
+    return Error::NONE;
+}
+
+Error FakeComposerClient::setLayerSourceCrop(Display /*display*/, Layer layer,
+                                             const hwc_frect_t& crop) {
+    ALOGV("setLayerSourceCrop");
+    getLayerImpl(layer).mRenderState.mSourceCrop = crop;
+    return Error::NONE;
+}
+
+Error FakeComposerClient::setLayerTransform(Display /*display*/, Layer layer, int32_t transform) {
+    ALOGV("setLayerTransform");
+    getLayerImpl(layer).mRenderState.mTransform = static_cast<hwc_transform_t>(transform);
+    return Error::NONE;
+}
+
+Error FakeComposerClient::setLayerVisibleRegion(Display /*display*/, Layer layer,
+                                                const std::vector<hwc_rect_t>& visible) {
+    ALOGV("setLayerVisibleRegion");
+    getLayerImpl(layer).mRenderState.mVisibleRegion = visible;
+    return Error::NONE;
+}
+
+Error FakeComposerClient::setLayerZOrder(Display /*display*/, Layer layer, uint32_t z) {
+    ALOGV("setLayerZOrder");
+    getLayerImpl(layer).mZ = z;
+    return Error::NONE;
+}
+
+//////////////////////////////////////////////////////////////////
+
+void FakeComposerClient::setClient(ComposerClient* client) {
+    mClient = client;
+}
+
+void FakeComposerClient::requestVSync(uint64_t vsyncTime) {
+    if (mCallbacksOn) {
+        uint64_t timestamp = vsyncTime;
+        ALOGV("Vsync");
+        if (timestamp == 0) {
+            struct timespec ts;
+            clock_gettime(CLOCK_MONOTONIC, &ts);
+            timestamp = ts.tv_sec * 1000 * 1000 * 1000 + ts.tv_nsec;
+        }
+        if (mSurfaceComposer != nullptr) {
+            mSurfaceComposer->injectVSync(timestamp);
+        } else {
+            mClient->onVsync(DEFAULT_DISPLAY, timestamp);
+        }
+    }
+}
+
+void FakeComposerClient::runVSyncAfter(std::chrono::nanoseconds wait) {
+    mDelayedEventGenerator->wakeAfter(wait);
+}
+
+LayerImpl& FakeComposerClient::getLayerImpl(Layer handle) {
+    // TODO Change these to an internal state check that can be
+    // invoked from the gtest? GTest macros do not seem all that safe
+    // when used outside the test class
+    EXPECT_GE(handle, static_cast<Layer>(0));
+    EXPECT_LT(handle, mLayers.size());
+    return *(mLayers[handle]);
+}
+
+int FakeComposerClient::getFrameCount() const {
+    return mFrames.size();
+}
+
+static std::vector<RenderState> extractRenderState(
+        const std::vector<std::unique_ptr<FrameRect>>& internalRects) {
+    std::vector<RenderState> result;
+    result.reserve(internalRects.size());
+    for (const std::unique_ptr<FrameRect>& rect : internalRects) {
+        result.push_back(rect->renderState);
+    }
+    return result;
+}
+
+std::vector<RenderState> FakeComposerClient::getFrameRects(int frame) const {
+    Mutex::Autolock _l(mStateMutex);
+    return extractRenderState(mFrames[frame]->rectangles);
+}
+
+std::vector<RenderState> FakeComposerClient::getLatestFrame() const {
+    Mutex::Autolock _l(mStateMutex);
+    return extractRenderState(mFrames[mFrames.size() - 1]->rectangles);
+}
+
+void FakeComposerClient::runVSyncAndWait(std::chrono::nanoseconds maxWait) {
+    int currentFrame = 0;
+    {
+        Mutex::Autolock _l(mStateMutex); // I hope this is ok...
+        currentFrame = static_cast<int>(mFrames.size());
+        requestVSync();
+    }
+    waitUntilFrame(currentFrame + 1, maxWait);
+}
+
+void FakeComposerClient::waitUntilFrame(int targetFrame, std::chrono::nanoseconds maxWait) const {
+    Mutex::Autolock _l(mStateMutex);
+    while (mFrames.size() < static_cast<size_t>(targetFrame)) {
+        android::status_t result = mFramesAvailable.waitRelative(mStateMutex, maxWait.count());
+        if (result == android::TIMED_OUT) {
+            ALOGE("Waiting for frame %d (at frame %zu now) timed out after %lld ns", targetFrame,
+                  mFrames.size(), maxWait.count());
+            return;
+        }
+    }
+}
+
+void FakeComposerClient::clearFrames() {
+    Mutex::Autolock _l(mStateMutex);
+    mFrames.clear();
+    for (const std::unique_ptr<LayerImpl>& layer : mLayers) {
+        if (layer->mValid) {
+            layer->mRenderState.mSwapCount = 0;
+        }
+    }
+}
+
+void FakeComposerClient::onSurfaceFlingerStart() {
+    mSurfaceComposer == nullptr;
+    do {
+        mSurfaceComposer = new android::SurfaceComposerClient;
+        android::status_t initResult = mSurfaceComposer->initCheck();
+        if (initResult != android::NO_ERROR) {
+            ALOGD("Init result: %d", initResult);
+            mSurfaceComposer = nullptr;
+            std::this_thread::sleep_for(10ms);
+        }
+    } while (mSurfaceComposer == nullptr);
+    ALOGD("SurfaceComposerClient created");
+    mSurfaceComposer->enableVSyncInjections(true);
+}
+
+void FakeComposerClient::onSurfaceFlingerStop() {
+    mSurfaceComposer->dispose();
+    mSurfaceComposer.clear();
+}
+
+// Includes destroyed layers, stored in order of creation.
+int FakeComposerClient::getLayerCount() const {
+    return mLayers.size();
+}
+
+Layer FakeComposerClient::getLayer(size_t index) const {
+    // NOTE: If/when passing calls through to actual implementation,
+    // this might get more involving.
+    return static_cast<Layer>(index);
+}
diff --git a/services/surfaceflinger/tests/fakehwc/FakeComposerClient.h b/services/surfaceflinger/tests/fakehwc/FakeComposerClient.h
new file mode 100644
index 0000000..294abb2
--- /dev/null
+++ b/services/surfaceflinger/tests/fakehwc/FakeComposerClient.h
@@ -0,0 +1,146 @@
+/*
+ * Copyright 2017 The Android Open Source Project
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *      http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+#pragma once
+
+#include "ComposerClient.h"
+#include "RenderState.h"
+
+#include <utils/Condition.h>
+
+#include <chrono>
+
+using namespace android::hardware::graphics::composer::V2_1;
+using namespace android::hardware::graphics::composer::V2_1::implementation;
+using namespace android::hardware;
+using namespace std::chrono_literals;
+
+namespace {
+class LayerImpl;
+class Frame;
+class DelayedEventGenerator;
+} // namespace
+
+namespace android {
+class SurfaceComposerClient;
+} // namespace android
+
+namespace sftest {
+
+class FakeComposerClient : public ComposerBase {
+public:
+    FakeComposerClient();
+    virtual ~FakeComposerClient();
+
+    void removeClient() override;
+    void enableCallback(bool enable) override;
+    uint32_t getMaxVirtualDisplayCount() override;
+    Error createVirtualDisplay(uint32_t width, uint32_t height, PixelFormat* format,
+                               Display* outDisplay) override;
+    Error destroyVirtualDisplay(Display display) override;
+    Error createLayer(Display display, Layer* outLayer) override;
+    Error destroyLayer(Display display, Layer layer) override;
+
+    Error getActiveConfig(Display display, Config* outConfig) override;
+    Error getClientTargetSupport(Display display, uint32_t width, uint32_t height,
+                                 PixelFormat format, Dataspace dataspace) override;
+    Error getColorModes(Display display, hidl_vec<ColorMode>* outModes) override;
+    Error getDisplayAttribute(Display display, Config config, IComposerClient::Attribute attribute,
+                              int32_t* outValue) override;
+    Error getDisplayConfigs(Display display, hidl_vec<Config>* outConfigs) override;
+    Error getDisplayName(Display display, hidl_string* outName) override;
+    Error getDisplayType(Display display, IComposerClient::DisplayType* outType) override;
+    Error getDozeSupport(Display display, bool* outSupport) override;
+    Error getHdrCapabilities(Display display, hidl_vec<Hdr>* outTypes, float* outMaxLuminance,
+                             float* outMaxAverageLuminance, float* outMinLuminance) override;
+
+    Error setActiveConfig(Display display, Config config) override;
+    Error setColorMode(Display display, ColorMode mode) override;
+    Error setPowerMode(Display display, IComposerClient::PowerMode mode) override;
+    Error setVsyncEnabled(Display display, IComposerClient::Vsync enabled) override;
+
+    Error setColorTransform(Display display, const float* matrix, int32_t hint) override;
+    Error setClientTarget(Display display, buffer_handle_t target, int32_t acquireFence,
+                          int32_t dataspace, const std::vector<hwc_rect_t>& damage) override;
+    Error setOutputBuffer(Display display, buffer_handle_t buffer, int32_t releaseFence) override;
+    Error validateDisplay(Display display, std::vector<Layer>* outChangedLayers,
+                          std::vector<IComposerClient::Composition>* outCompositionTypes,
+                          uint32_t* outDisplayRequestMask, std::vector<Layer>* outRequestedLayers,
+                          std::vector<uint32_t>* outRequestMasks) override;
+    Error acceptDisplayChanges(Display display) override;
+    Error presentDisplay(Display display, int32_t* outPresentFence, std::vector<Layer>* outLayers,
+                         std::vector<int32_t>* outReleaseFences) override;
+
+    Error setLayerCursorPosition(Display display, Layer layer, int32_t x, int32_t y) override;
+    Error setLayerBuffer(Display display, Layer layer, buffer_handle_t buffer,
+                         int32_t acquireFence) override;
+    Error setLayerSurfaceDamage(Display display, Layer layer,
+                                const std::vector<hwc_rect_t>& damage) override;
+    Error setLayerBlendMode(Display display, Layer layer, int32_t mode) override;
+    Error setLayerColor(Display display, Layer layer, IComposerClient::Color color) override;
+    Error setLayerCompositionType(Display display, Layer layer, int32_t type) override;
+    Error setLayerDataspace(Display display, Layer layer, int32_t dataspace) override;
+    Error setLayerDisplayFrame(Display display, Layer layer, const hwc_rect_t& frame) override;
+    Error setLayerPlaneAlpha(Display display, Layer layer, float alpha) override;
+    Error setLayerSidebandStream(Display display, Layer layer, buffer_handle_t stream) override;
+    Error setLayerSourceCrop(Display display, Layer layer, const hwc_frect_t& crop) override;
+    Error setLayerTransform(Display display, Layer layer, int32_t transform) override;
+    Error setLayerVisibleRegion(Display display, Layer layer,
+                                const std::vector<hwc_rect_t>& visible) override;
+    Error setLayerZOrder(Display display, Layer layer, uint32_t z) override;
+
+    void setClient(ComposerClient* client);
+
+    void requestVSync(uint64_t vsyncTime = 0);
+    // We don't want tests hanging, so always use a timeout. Remember
+    // to always check the number of frames with test ASSERT_!
+    // Wait until next frame is rendered after requesting vsync.
+    void runVSyncAndWait(std::chrono::nanoseconds maxWait = 100ms);
+    void runVSyncAfter(std::chrono::nanoseconds wait);
+
+    int getFrameCount() const;
+    // We don't want tests hanging, so always use a timeout. Remember
+    // to always check the number of frames with test ASSERT_!
+    void waitUntilFrame(int targetFrame, std::chrono::nanoseconds maxWait = 100ms) const;
+    std::vector<RenderState> getFrameRects(int frame) const;
+    std::vector<RenderState> getLatestFrame() const;
+    void clearFrames();
+
+    void onSurfaceFlingerStart();
+    void onSurfaceFlingerStop();
+
+    int getLayerCount() const;
+    Layer getLayer(size_t index) const;
+
+    void hotplugDisplay(Display display, IComposerCallback::Connection state);
+
+private:
+    LayerImpl& getLayerImpl(Layer handle);
+
+    bool mCallbacksOn;
+    ComposerClient* mClient;
+    Config mCurrentConfig;
+    bool mVsyncEnabled;
+    std::vector<std::unique_ptr<LayerImpl>> mLayers;
+    std::vector<std::unique_ptr<Frame>> mFrames;
+    // Using a pointer to hide the implementation into the CPP file.
+    std::unique_ptr<DelayedEventGenerator> mDelayedEventGenerator;
+    android::sp<android::SurfaceComposerClient> mSurfaceComposer; // For VSync injections
+    mutable android::Mutex mStateMutex;
+    mutable android::Condition mFramesAvailable;
+};
+
+} // namespace sftest
diff --git a/services/surfaceflinger/tests/fakehwc/FakeComposerService.cpp b/services/surfaceflinger/tests/fakehwc/FakeComposerService.cpp
new file mode 100644
index 0000000..c411604
--- /dev/null
+++ b/services/surfaceflinger/tests/fakehwc/FakeComposerService.cpp
@@ -0,0 +1,54 @@
+/*
+ * Copyright (C) 2017 The Android Open Source Project
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *      http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+#define LOG_NDEBUG 0
+#undef LOG_TAG
+#define LOG_TAG "FakeHwcService"
+#include <log/log.h>
+
+#include "FakeComposerService.h"
+
+using namespace android::hardware;
+
+namespace sftest {
+
+FakeComposerService::FakeComposerService(android::sp<ComposerClient>& client) : mClient(client) {}
+
+FakeComposerService::~FakeComposerService() {
+    ALOGI("Maybe killing client %p", mClient.get());
+    // Rely on sp to kill the client.
+}
+
+Return<void> FakeComposerService::getCapabilities(getCapabilities_cb hidl_cb) {
+    ALOGI("FakeComposerService::getCapabilities");
+    hidl_cb(hidl_vec<Capability>());
+    return Void();
+}
+
+Return<void> FakeComposerService::dumpDebugInfo(dumpDebugInfo_cb hidl_cb) {
+    ALOGI("FakeComposerService::dumpDebugInfo");
+    hidl_cb(hidl_string());
+    return Void();
+}
+
+Return<void> FakeComposerService::createClient(createClient_cb hidl_cb) {
+    ALOGI("FakeComposerService::createClient %p", mClient.get());
+    mClient->initialize();
+    hidl_cb(Error::NONE, mClient);
+    return Void();
+}
+
+} // namespace sftest
diff --git a/services/surfaceflinger/tests/fakehwc/FakeComposerService.h b/services/surfaceflinger/tests/fakehwc/FakeComposerService.h
new file mode 100644
index 0000000..5204084
--- /dev/null
+++ b/services/surfaceflinger/tests/fakehwc/FakeComposerService.h
@@ -0,0 +1,40 @@
+/*
+ * Copyright (C) 2017 The Android Open Source Project
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *      http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+#pragma once
+
+#include "ComposerClient.h"
+
+using namespace android::hardware::graphics::composer::V2_1;
+using namespace android::hardware::graphics::composer::V2_1::implementation;
+using android::hardware::Return;
+
+namespace sftest {
+
+class FakeComposerService : public IComposer {
+public:
+    FakeComposerService(android::sp<ComposerClient>& client);
+    virtual ~FakeComposerService();
+
+    Return<void> getCapabilities(getCapabilities_cb hidl_cb) override;
+    Return<void> dumpDebugInfo(dumpDebugInfo_cb hidl_cb) override;
+    Return<void> createClient(createClient_cb hidl_cb) override;
+
+private:
+    android::sp<ComposerClient> mClient;
+};
+
+} // namespace sftest
diff --git a/services/surfaceflinger/tests/fakehwc/FakeComposerUtils.cpp b/services/surfaceflinger/tests/fakehwc/FakeComposerUtils.cpp
new file mode 100644
index 0000000..51956ec
--- /dev/null
+++ b/services/surfaceflinger/tests/fakehwc/FakeComposerUtils.cpp
@@ -0,0 +1,183 @@
+/*
+ * Copyright 2017 The Android Open Source Project
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *      http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+#define LOG_NDEBUG 0
+#undef LOG_TAG
+#define LOG_TAG "FakeHwcUtil"
+#include <log/log.h>
+
+#include "FakeComposerUtils.h"
+#include "RenderState.h"
+
+#include "SurfaceFlinger.h" // Get the name of the service...
+
+#include <binder/IServiceManager.h>
+
+#include <cutils/properties.h>
+
+#include <iomanip>
+#include <thread>
+
+using android::String16;
+using android::sp;
+using namespace std::chrono_literals;
+using namespace sftest;
+using std::setw;
+
+namespace sftest {
+
+// clang-format off
+inline void printSourceRectAligned(::std::ostream& os, const hwc_frect_t& sourceRect, int align) {
+    os << std::fixed << std::setprecision(1) << "("
+       << setw(align) << sourceRect.left << setw(0) << ","
+       << setw(align) << sourceRect.top << setw(0) << ","
+       << setw(align) << sourceRect.right << setw(0) << ","
+       << setw(align) << sourceRect.bottom << setw(0) << ")";
+}
+
+inline void printDisplayRectAligned(::std::ostream& os, const hwc_rect_t& displayRect, int align) {
+    os << "("
+       << setw(align) << displayRect.left << setw(0) << ","
+       << setw(align) << displayRect.top << setw(0) << ","
+       << setw(align) << displayRect.right << setw(0) << ","
+       << setw(align) << displayRect.bottom << setw(0) << ")";
+}
+// clang-format on
+
+inline ::std::ostream& operator<<(::std::ostream& os, const sftest::RenderState& state) {
+    printSourceRectAligned(os, state.mSourceCrop, 7);
+    os << "->";
+    printDisplayRectAligned(os, state.mDisplayFrame, 5);
+    return os << " Swaps:" << state.mSwapCount << " Alpha:" << std::setprecision(3)
+              << state.mPlaneAlpha << " Xform:" << state.mTransform;
+}
+
+// Helper for verifying the parts of the RenderState
+template <typename T>
+bool valuesMatch(::testing::AssertionResult& message, const T& ref, const T& val,
+                 const char* name) {
+    if (ref != val) {
+        message = message << "Expected " << name << ":" << ref << ", got:" << val << ".";
+        return false;
+    }
+    return true;
+}
+
+::testing::AssertionResult rectsAreSame(const RenderState& ref, const RenderState& val) {
+    // TODO: Message could start as success and be assigned as failure.
+    // Only problem is that utility assumes it to be failure and just adds stuff. Would
+    // need still special case the initial failure in the utility?
+    // TODO: ... or would it be possible to break this back to gtest primitives?
+    ::testing::AssertionResult message = ::testing::AssertionFailure();
+    bool passes = true;
+
+    // The work here is mostly about providing good log strings for differences
+    passes &= valuesMatch(message, ref.mDisplayFrame, val.mDisplayFrame, "display frame");
+    passes &= valuesMatch(message, ref.mPlaneAlpha, val.mPlaneAlpha, "alpha");
+    passes &= valuesMatch(message, ref.mSwapCount, val.mSwapCount, "swap count");
+    passes &= valuesMatch(message, ref.mSourceCrop, val.mSourceCrop, "source crop");
+    // ... add more
+    if (passes) {
+        return ::testing::AssertionSuccess();
+    }
+    return message;
+}
+
+::testing::AssertionResult framesAreSame(const std::vector<RenderState>& ref,
+                                         const std::vector<RenderState>& val) {
+    ::testing::AssertionResult message = ::testing::AssertionFailure();
+    bool passed = true;
+    if (ref.size() != val.size()) {
+        message << "Expected " << ref.size() << " rects, got " << val.size() << ".";
+        passed = false;
+    }
+    for (size_t rectIndex = 0; rectIndex < std::min(ref.size(), val.size()); rectIndex++) {
+        ::testing::AssertionResult rectResult = rectsAreSame(ref[rectIndex], val[rectIndex]);
+        if (rectResult == false) {
+            message << "First different rect at " << rectIndex << ": " << rectResult.message();
+            passed = false;
+            break;
+        }
+    }
+
+    if (passed) {
+        return ::testing::AssertionSuccess();
+    } else {
+        message << "\nReference:";
+        for (auto state = ref.begin(); state != ref.end(); ++state) {
+            message << "\n" << *state;
+        }
+        message << "\nActual:";
+        for (auto state = val.begin(); state != val.end(); ++state) {
+            message << "\n" << *state;
+        }
+    }
+    return message;
+}
+
+void startSurfaceFlinger() {
+    ALOGI("Start SurfaceFlinger");
+    system("start surfaceflinger");
+
+    sp<android::IServiceManager> sm(android::defaultServiceManager());
+    sp<android::IBinder> sf;
+    while (sf == nullptr) {
+        std::this_thread::sleep_for(10ms);
+        sf = sm->checkService(String16(android::SurfaceFlinger::getServiceName()));
+    }
+    ALOGV("SurfaceFlinger running");
+}
+
+void stopSurfaceFlinger() {
+    ALOGI("Stop SurfaceFlinger");
+    system("stop surfaceflinger");
+    sp<android::IServiceManager> sm(android::defaultServiceManager());
+    sp<android::IBinder> sf;
+    while (sf != nullptr) {
+        std::this_thread::sleep_for(10ms);
+        sf = sm->checkService(String16(android::SurfaceFlinger::getServiceName()));
+    }
+    ALOGV("SurfaceFlinger stopped");
+}
+
+////////////////////////////////////////////////
+
+void FakeHwcEnvironment::SetUp() {
+    ALOGI("Test env setup");
+    system("setenforce 0");
+    system("stop");
+    property_set("debug.sf.nobootanimation", "1");
+    {
+        char value[PROPERTY_VALUE_MAX];
+        property_get("debug.sf.nobootanimation", value, "0");
+        LOG_FATAL_IF(atoi(value) != 1, "boot skip not set");
+    }
+    // TODO: Try registering the mock as the default service instead.
+    property_set("debug.sf.hwc_service_name", "mock");
+    // This allows the SurfaceFlinger to load a HIDL service not listed in manifest files.
+    property_set("debug.sf.treble_testing_override", "true");
+}
+
+void FakeHwcEnvironment::TearDown() {
+    ALOGI("Test env tear down");
+    system("stop");
+    // Wait for mock call signaling teardown?
+    property_set("debug.sf.nobootanimation", "0");
+    property_set("debug.sf.hwc_service_name", "default");
+    ALOGI("Test env tear down - done");
+}
+
+} // namespace sftest
diff --git a/services/surfaceflinger/tests/fakehwc/FakeComposerUtils.h b/services/surfaceflinger/tests/fakehwc/FakeComposerUtils.h
new file mode 100644
index 0000000..74dc0e5
--- /dev/null
+++ b/services/surfaceflinger/tests/fakehwc/FakeComposerUtils.h
@@ -0,0 +1,119 @@
+/*
+ * Copyright 2017 The Android Open Source Project
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *      http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+#pragma once
+
+#include "FakeComposerClient.h"
+
+#include <gui/SurfaceComposerClient.h>
+
+#include <hardware/hwcomposer_defs.h>
+
+#include <log/log.h>
+
+#include <gtest/gtest.h>
+
+// clang-format off
+// Note: This needs to reside in the global namespace for the GTest to use it
+inline ::std::ostream& operator<<(::std::ostream& os, const hwc_rect_t& rect) {
+    return os << "(" << rect.left << ","
+              << rect.top << ","
+              << rect.right << ","
+              << rect.bottom << ")";
+}
+
+inline ::std::ostream& operator<<(::std::ostream& os, const hwc_frect_t& rect) {
+    return os << "(" << rect.left << ","
+              << rect.top << ","
+              << rect.right << ","
+              << rect.bottom << ")";
+}
+// clang-format on
+
+namespace sftest {
+
+class RenderState;
+
+// clang-format off
+inline bool operator==(const hwc_rect_t& a, const hwc_rect_t& b) {
+    return a.top == b.top &&
+            a.left == b.left &&
+            a.bottom == b.bottom &&
+            a.right == b.right;
+}
+
+inline bool operator==(const hwc_frect_t& a, const hwc_frect_t& b) {
+    return a.top == b.top &&
+            a.left == b.left &&
+            a.bottom == b.bottom &&
+            a.right == b.right;
+}
+// clang-format on
+
+inline bool operator!=(const hwc_rect_t& a, const hwc_rect_t& b) {
+    return !(a == b);
+}
+
+inline bool operator!=(const hwc_frect_t& a, const hwc_frect_t& b) {
+    return !(a == b);
+}
+
+::testing::AssertionResult rectsAreSame(const RenderState& ref, const RenderState& val);
+::testing::AssertionResult framesAreSame(const std::vector<RenderState>& ref,
+                                         const std::vector<RenderState>& val);
+
+void startSurfaceFlinger();
+void stopSurfaceFlinger();
+
+class FakeHwcEnvironment : public ::testing::Environment {
+public:
+    virtual ~FakeHwcEnvironment() {}
+    void SetUp() override;
+    void TearDown() override;
+};
+
+/*
+ * All surface state changes are supposed to happen inside a global
+ * transaction. GlobalTransactionScope object at the beginning of
+ * scope automates the process. The resulting scope gives a visual cue
+ * on the span of the transaction as well.
+ *
+ * Closing the transaction is synchronous, i.e., it waits for
+ * SurfaceFlinger to composite one frame. Now, the FakeComposerClient
+ * is built to explicitly request vsyncs one at the time. A delayed
+ * request must be made before closing the transaction or the test
+ * thread stalls until SurfaceFlinger does an emergency vsync by
+ * itself. GlobalTransactionScope encapsulates this vsync magic.
+ */
+class GlobalTransactionScope {
+public:
+    GlobalTransactionScope(FakeComposerClient& composer) : mComposer(composer) {
+        android::SurfaceComposerClient::openGlobalTransaction();
+    }
+    ~GlobalTransactionScope() {
+        int frameCount = mComposer.getFrameCount();
+        mComposer.runVSyncAfter(1ms);
+        android::SurfaceComposerClient::closeGlobalTransaction(true);
+        // Make sure that exactly one frame has been rendered.
+        mComposer.waitUntilFrame(frameCount + 1);
+        LOG_ALWAYS_FATAL_IF(frameCount + 1 != mComposer.getFrameCount(),
+                            "Unexpected frame advance. Delta: %d",
+                            mComposer.getFrameCount() - frameCount);
+    }
+    FakeComposerClient& mComposer;
+};
+
+} // namespace sftest
diff --git a/services/surfaceflinger/tests/fakehwc/RenderState.h b/services/surfaceflinger/tests/fakehwc/RenderState.h
new file mode 100644
index 0000000..0059289
--- /dev/null
+++ b/services/surfaceflinger/tests/fakehwc/RenderState.h
@@ -0,0 +1,44 @@
+/*
+ * Copyright 2017 The Android Open Source Project
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *      http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+#pragma once
+
+#include <hardware/hwcomposer2.h>
+
+#include <vector>
+
+namespace sftest {
+// Description of a rendered rectangle.  Should only contain
+// instructions necessary to rasterize the rectangle. The full scene
+// is given as a sorted list of rectangles, bottom layer at index 0.
+class RenderState {
+public:
+    RenderState() = default;
+    // Default copy-ctor
+
+    hwc_rect_t mDisplayFrame = {0, 0, 0, 0};
+    hwc_frect_t mSourceCrop = {0.f, 0.f, 0.f, 0.f};
+    std::vector<hwc_rect_t> mVisibleRegion;
+    hwc2_blend_mode_t mBlendMode = HWC2_BLEND_MODE_NONE;
+    buffer_handle_t mBuffer = 0;
+    uint32_t mSwapCount = 0;   // How many set buffer calls to the layer.
+    int32_t mAcquireFence = 0; // Probably should not be here.
+    float mPlaneAlpha = 0.f;
+    hwc_color_t mLayerColor = {0, 0, 0, 0};
+    hwc_transform_t mTransform = static_cast<hwc_transform_t>(0);
+};
+
+} // namespace sftest
diff --git a/services/surfaceflinger/tests/fakehwc/SFFakeHwc_test.cpp b/services/surfaceflinger/tests/fakehwc/SFFakeHwc_test.cpp
new file mode 100644
index 0000000..8902ede
--- /dev/null
+++ b/services/surfaceflinger/tests/fakehwc/SFFakeHwc_test.cpp
@@ -0,0 +1,1306 @@
+/*
+ * Copyright (C) 2017 The Android Open Source Project
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *      http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+// #define LOG_NDEBUG 0
+#undef LOG_TAG
+#define LOG_TAG "FakeHwcTest"
+
+#include "FakeComposerClient.h"
+#include "FakeComposerService.h"
+#include "FakeComposerUtils.h"
+
+#include <gui/ISurfaceComposer.h>
+#include <gui/LayerDebugInfo.h>
+#include <gui/Surface.h>
+#include <gui/SurfaceComposerClient.h>
+
+#include <private/gui/ComposerService.h>
+#include <private/gui/LayerState.h>
+
+#include <ui/DisplayInfo.h>
+
+#include <android/native_window.h>
+
+#include <android/hidl/manager/1.0/IServiceManager.h>
+
+#include <hwbinder/ProcessState.h>
+
+#include <binder/ProcessState.h>
+
+#include <log/log.h>
+
+#include <gmock/gmock.h>
+#include <gtest/gtest.h>
+
+#include <limits>
+
+using namespace std::chrono_literals;
+
+using namespace android;
+using namespace android::hardware;
+
+using namespace sftest;
+
+namespace {
+
+// Mock test helpers
+using ::testing::Invoke;
+using ::testing::Return;
+using ::testing::SetArgPointee;
+using ::testing::_;
+
+///////////////////////////////////////////////
+
+struct TestColor {
+public:
+    uint8_t r;
+    uint8_t g;
+    uint8_t b;
+    uint8_t a;
+};
+
+constexpr static TestColor RED = {195, 63, 63, 255};
+constexpr static TestColor LIGHT_RED = {255, 177, 177, 255};
+constexpr static TestColor GREEN = {63, 195, 63, 255};
+constexpr static TestColor BLUE = {63, 63, 195, 255};
+constexpr static TestColor DARK_GRAY = {63, 63, 63, 255};
+constexpr static TestColor LIGHT_GRAY = {200, 200, 200, 255};
+
+// Fill an RGBA_8888 formatted surface with a single color.
+static void fillSurfaceRGBA8(const sp<SurfaceControl>& sc, const TestColor& color,
+                             bool unlock = true) {
+    ANativeWindow_Buffer outBuffer;
+    sp<Surface> s = sc->getSurface();
+    ASSERT_TRUE(s != nullptr);
+    ASSERT_EQ(NO_ERROR, s->lock(&outBuffer, nullptr));
+    uint8_t* img = reinterpret_cast<uint8_t*>(outBuffer.bits);
+    for (int y = 0; y < outBuffer.height; y++) {
+        for (int x = 0; x < outBuffer.width; x++) {
+            uint8_t* pixel = img + (4 * (y * outBuffer.stride + x));
+            pixel[0] = color.r;
+            pixel[1] = color.g;
+            pixel[2] = color.b;
+            pixel[3] = color.a;
+        }
+    }
+    if (unlock) {
+        ASSERT_EQ(NO_ERROR, s->unlockAndPost());
+    }
+}
+
+inline RenderState makeSimpleRect(int left, int top, int right, int bottom) {
+    RenderState res;
+    res.mDisplayFrame = hwc_rect_t{left, top, right, bottom};
+    res.mPlaneAlpha = 1.0f;
+    res.mSwapCount = 0;
+    res.mSourceCrop = hwc_frect_t{0.f, 0.f, static_cast<float>(right - left),
+                                  static_cast<float>(bottom - top)};
+    return res;
+}
+
+inline RenderState makeSimpleRect(unsigned int left, unsigned int top, unsigned int right,
+                                  unsigned int bottom) {
+    EXPECT_LE(left, static_cast<unsigned int>(INT_MAX));
+    EXPECT_LE(top, static_cast<unsigned int>(INT_MAX));
+    EXPECT_LE(right, static_cast<unsigned int>(INT_MAX));
+    EXPECT_LE(bottom, static_cast<unsigned int>(INT_MAX));
+    return makeSimpleRect(static_cast<int>(left), static_cast<int>(top), static_cast<int>(right),
+                          static_cast<int>(bottom));
+}
+
+////////////////////////////////////////////////
+
+class DisplayTest : public ::testing::Test {
+public:
+    class MockComposerClient : public FakeComposerClient {
+    public:
+        MOCK_METHOD2(getDisplayType, Error(Display display, ComposerClient::DisplayType* outType));
+        MOCK_METHOD4(getDisplayAttribute,
+                     Error(Display display, Config config, IComposerClient::Attribute attribute,
+                           int32_t* outValue));
+
+        // Re-routing to basic fake implementation
+        Error getDisplayAttributeFake(Display display, Config config,
+                                      IComposerClient::Attribute attribute, int32_t* outValue) {
+            return FakeComposerClient::getDisplayAttribute(display, config, attribute, outValue);
+        }
+    };
+
+protected:
+    void SetUp() override;
+    void TearDown() override;
+
+    sp<IComposer> mFakeService;
+    sp<SurfaceComposerClient> mComposerClient;
+
+    MockComposerClient* mMockComposer;
+};
+
+void DisplayTest::SetUp() {
+    // TODO: The mMockComposer should be a unique_ptr, but it needs to
+    // outlive the test class.  Currently ComposerClient only dies
+    // when the service is replaced. The Mock deletes itself when
+    // removeClient is called on it, which is ugly.  This can be
+    // changed if HIDL ServiceManager allows removing services or
+    // ComposerClient starts taking the ownership of the contained
+    // implementation class. Moving the fake class to the HWC2
+    // interface instead of the current Composer interface might also
+    // change the situation.
+    mMockComposer = new MockComposerClient;
+    sp<ComposerClient> client = new ComposerClient(*mMockComposer);
+    mMockComposer->setClient(client.get());
+    mFakeService = new FakeComposerService(client);
+    mFakeService->registerAsService("mock");
+
+    android::hardware::ProcessState::self()->startThreadPool();
+    android::ProcessState::self()->startThreadPool();
+
+    EXPECT_CALL(*mMockComposer, getDisplayType(1, _))
+            .WillOnce(DoAll(SetArgPointee<1>(IComposerClient::DisplayType::PHYSICAL),
+                            Return(Error::NONE)));
+    // Seems to be doubled right now, once for display ID 1 and once for 0. This sounds fishy
+    // but encoding that here exactly.
+    EXPECT_CALL(*mMockComposer, getDisplayAttribute(1, 1, _, _))
+            .Times(5)
+            .WillRepeatedly(Invoke(mMockComposer, &MockComposerClient::getDisplayAttributeFake));
+    // TODO: Find out what code is generating the ID 0.
+    EXPECT_CALL(*mMockComposer, getDisplayAttribute(0, 1, _, _))
+            .Times(5)
+            .WillRepeatedly(Invoke(mMockComposer, &MockComposerClient::getDisplayAttributeFake));
+
+    startSurfaceFlinger();
+
+    // Fake composer wants to enable VSync injection
+    mMockComposer->onSurfaceFlingerStart();
+
+    mComposerClient = new SurfaceComposerClient;
+    ASSERT_EQ(NO_ERROR, mComposerClient->initCheck());
+}
+
+void DisplayTest::TearDown() {
+    mComposerClient->dispose();
+    mComposerClient = nullptr;
+
+    // Fake composer needs to release SurfaceComposerClient before the stop.
+    mMockComposer->onSurfaceFlingerStop();
+    stopSurfaceFlinger();
+
+    mFakeService = nullptr;
+    // TODO: Currently deleted in FakeComposerClient::removeClient(). Devise better lifetime
+    // management.
+    mMockComposer = nullptr;
+}
+
+TEST_F(DisplayTest, Hotplug) {
+    ALOGD("DisplayTest::Hotplug");
+
+    EXPECT_CALL(*mMockComposer, getDisplayType(2, _))
+            .Times(2)
+            .WillRepeatedly(DoAll(SetArgPointee<1>(IComposerClient::DisplayType::PHYSICAL),
+                                  Return(Error::NONE)));
+    // The attribute queries will get done twice. This is for defaults
+    EXPECT_CALL(*mMockComposer, getDisplayAttribute(2, 1, _, _))
+            .Times(2 * 3)
+            .WillRepeatedly(Invoke(mMockComposer, &MockComposerClient::getDisplayAttributeFake));
+    // ... and then special handling for dimensions. Specifying this
+    // rules later means that gmock will try them first, i.e.,
+    // ordering of width/height vs. the default implementation for
+    // other queries is significant.
+    EXPECT_CALL(*mMockComposer, getDisplayAttribute(2, 1, IComposerClient::Attribute::WIDTH, _))
+            .Times(2)
+            .WillRepeatedly(DoAll(SetArgPointee<3>(400), Return(Error::NONE)));
+
+    EXPECT_CALL(*mMockComposer, getDisplayAttribute(2, 1, IComposerClient::Attribute::HEIGHT, _))
+            .Times(2)
+            .WillRepeatedly(DoAll(SetArgPointee<3>(200), Return(Error::NONE)));
+
+    // TODO: Width and height queries are not actually called. Display
+    // info returns dimensions 0x0 in display info. Why?
+
+    mMockComposer->hotplugDisplay(static_cast<Display>(2),
+                                  IComposerCallback::Connection::CONNECTED);
+
+    {
+        sp<android::IBinder> display(
+                SurfaceComposerClient::getBuiltInDisplay(ISurfaceComposer::eDisplayIdHdmi));
+        DisplayInfo info;
+        SurfaceComposerClient::getDisplayInfo(display, &info);
+        ASSERT_EQ(400u, info.w);
+        ASSERT_EQ(200u, info.h);
+
+        auto surfaceControl =
+                mComposerClient->createSurface(String8("Display Test Surface Foo"), info.w, info.h,
+                                               PIXEL_FORMAT_RGBA_8888, 0);
+        ASSERT_TRUE(surfaceControl != nullptr);
+        ASSERT_TRUE(surfaceControl->isValid());
+        fillSurfaceRGBA8(surfaceControl, BLUE);
+
+        {
+            GlobalTransactionScope gts(*mMockComposer);
+            mComposerClient->setDisplayLayerStack(display, 0);
+
+            ASSERT_EQ(NO_ERROR, surfaceControl->setLayer(INT32_MAX - 2));
+            ASSERT_EQ(NO_ERROR, surfaceControl->show());
+        }
+    }
+
+    mMockComposer->hotplugDisplay(static_cast<Display>(2),
+                                  IComposerCallback::Connection::DISCONNECTED);
+
+    mMockComposer->clearFrames();
+
+    mMockComposer->hotplugDisplay(static_cast<Display>(2),
+                                  IComposerCallback::Connection::CONNECTED);
+
+    {
+        sp<android::IBinder> display(
+                SurfaceComposerClient::getBuiltInDisplay(ISurfaceComposer::eDisplayIdHdmi));
+        DisplayInfo info;
+        SurfaceComposerClient::getDisplayInfo(display, &info);
+        ASSERT_EQ(400u, info.w);
+        ASSERT_EQ(200u, info.h);
+
+        auto surfaceControl =
+                mComposerClient->createSurface(String8("Display Test Surface Bar"), info.w, info.h,
+                                               PIXEL_FORMAT_RGBA_8888, 0);
+        ASSERT_TRUE(surfaceControl != nullptr);
+        ASSERT_TRUE(surfaceControl->isValid());
+        fillSurfaceRGBA8(surfaceControl, BLUE);
+
+        {
+            GlobalTransactionScope gts(*mMockComposer);
+            mComposerClient->setDisplayLayerStack(display, 0);
+
+            ASSERT_EQ(NO_ERROR, surfaceControl->setLayer(INT32_MAX - 2));
+            ASSERT_EQ(NO_ERROR, surfaceControl->show());
+        }
+    }
+    mMockComposer->hotplugDisplay(static_cast<Display>(2),
+                                  IComposerCallback::Connection::DISCONNECTED);
+}
+
+////////////////////////////////////////////////
+
+class TransactionTest : public ::testing::Test {
+protected:
+    // Layer array indexing constants.
+    constexpr static int BG_LAYER = 0;
+    constexpr static int FG_LAYER = 1;
+
+    static void SetUpTestCase();
+    static void TearDownTestCase();
+
+    void SetUp() override;
+    void TearDown() override;
+
+    sp<SurfaceComposerClient> mComposerClient;
+    sp<SurfaceControl> mBGSurfaceControl;
+    sp<SurfaceControl> mFGSurfaceControl;
+    std::vector<RenderState> mBaseFrame;
+    uint32_t mDisplayWidth;
+    uint32_t mDisplayHeight;
+
+    static FakeComposerClient* sFakeComposer;
+};
+
+FakeComposerClient* TransactionTest::sFakeComposer;
+
+void TransactionTest::SetUpTestCase() {
+    // TODO: See TODO comment at DisplayTest::SetUp for background on
+    // the lifetime of the FakeComposerClient.
+    sFakeComposer = new FakeComposerClient;
+    sp<ComposerClient> client = new ComposerClient(*sFakeComposer);
+    sFakeComposer->setClient(client.get());
+    sp<IComposer> fakeService = new FakeComposerService(client);
+    fakeService->registerAsService("mock");
+
+    android::hardware::ProcessState::self()->startThreadPool();
+    android::ProcessState::self()->startThreadPool();
+
+    startSurfaceFlinger();
+
+    // Fake composer wants to enable VSync injection
+    sFakeComposer->onSurfaceFlingerStart();
+}
+
+void TransactionTest::TearDownTestCase() {
+    // Fake composer needs to release SurfaceComposerClient before the stop.
+    sFakeComposer->onSurfaceFlingerStop();
+    stopSurfaceFlinger();
+    // TODO: This is deleted when the ComposerClient calls
+    // removeClient. Devise better lifetime control.
+    sFakeComposer = nullptr;
+}
+
+void TransactionTest::SetUp() {
+    ALOGI("TransactionTest::SetUp");
+    mComposerClient = new SurfaceComposerClient;
+    ASSERT_EQ(NO_ERROR, mComposerClient->initCheck());
+
+    ALOGI("TransactionTest::SetUp - display");
+    sp<android::IBinder> display(
+            SurfaceComposerClient::getBuiltInDisplay(ISurfaceComposer::eDisplayIdMain));
+    DisplayInfo info;
+    SurfaceComposerClient::getDisplayInfo(display, &info);
+
+    mDisplayWidth = info.w;
+    mDisplayHeight = info.h;
+
+    // Background surface
+    mBGSurfaceControl = mComposerClient->createSurface(String8("BG Test Surface"), mDisplayWidth,
+                                                       mDisplayHeight, PIXEL_FORMAT_RGBA_8888, 0);
+    ASSERT_TRUE(mBGSurfaceControl != nullptr);
+    ASSERT_TRUE(mBGSurfaceControl->isValid());
+    fillSurfaceRGBA8(mBGSurfaceControl, BLUE);
+
+    // Foreground surface
+    mFGSurfaceControl = mComposerClient->createSurface(String8("FG Test Surface"), 64, 64,
+                                                       PIXEL_FORMAT_RGBA_8888, 0);
+    ASSERT_TRUE(mFGSurfaceControl != nullptr);
+    ASSERT_TRUE(mFGSurfaceControl->isValid());
+
+    fillSurfaceRGBA8(mFGSurfaceControl, RED);
+
+    SurfaceComposerClient::openGlobalTransaction();
+
+    mComposerClient->setDisplayLayerStack(display, 0);
+
+    ASSERT_EQ(NO_ERROR, mBGSurfaceControl->setLayer(INT32_MAX - 2));
+    ASSERT_EQ(NO_ERROR, mBGSurfaceControl->show());
+
+    ASSERT_EQ(NO_ERROR, mFGSurfaceControl->setLayer(INT32_MAX - 1));
+    ASSERT_EQ(NO_ERROR, mFGSurfaceControl->setPosition(64, 64));
+    ASSERT_EQ(NO_ERROR, mFGSurfaceControl->show());
+
+    // Synchronous transaction will stop this thread, so we set up a
+    // delayed, off-thread vsync request before closing the
+    // transaction. In the test code this is usually done with
+    // GlobalTransactionScope. Leaving here in the 'vanilla' form for
+    // reference.
+    ASSERT_EQ(0, sFakeComposer->getFrameCount());
+    sFakeComposer->runVSyncAfter(1ms);
+    SurfaceComposerClient::closeGlobalTransaction(true);
+    sFakeComposer->waitUntilFrame(1);
+
+    // Reference data. This is what the HWC should see.
+    static_assert(BG_LAYER == 0 && FG_LAYER == 1, "Unexpected enum values for array indexing");
+    mBaseFrame.push_back(makeSimpleRect(0u, 0u, mDisplayWidth, mDisplayHeight));
+    mBaseFrame[BG_LAYER].mSwapCount = 1;
+    mBaseFrame.push_back(makeSimpleRect(64, 64, 64 + 64, 64 + 64));
+    mBaseFrame[FG_LAYER].mSwapCount = 1;
+
+    auto frame = sFakeComposer->getFrameRects(0);
+    ASSERT_TRUE(framesAreSame(mBaseFrame, frame));
+}
+
+void TransactionTest::TearDown() {
+    ALOGD("TransactionTest::TearDown");
+
+    mComposerClient->dispose();
+    mBGSurfaceControl = 0;
+    mFGSurfaceControl = 0;
+    mComposerClient = 0;
+
+    sFakeComposer->runVSyncAndWait();
+    mBaseFrame.clear();
+    sFakeComposer->clearFrames();
+    ASSERT_EQ(0, sFakeComposer->getFrameCount());
+
+    sp<ISurfaceComposer> sf(ComposerService::getComposerService());
+    std::vector<LayerDebugInfo> layers;
+    status_t result = sf->getLayerDebugInfo(&layers);
+    if (result != NO_ERROR) {
+        ALOGE("Failed to get layers %s %d", strerror(-result), result);
+    } else {
+        // If this fails, the test being torn down leaked layers.
+        EXPECT_EQ(0u, layers.size());
+        if (layers.size() > 0) {
+            for (auto layer = layers.begin(); layer != layers.end(); ++layer) {
+                std::cout << to_string(*layer).c_str();
+            }
+            // To ensure the next test has clean slate, will run the class
+            // tear down and setup here.
+            TearDownTestCase();
+            SetUpTestCase();
+        }
+    }
+    ALOGD("TransactionTest::TearDown - complete");
+}
+
+TEST_F(TransactionTest, LayerMove) {
+    ALOGD("TransactionTest::LayerMove");
+
+    // The scope opens and closes a global transaction and, at the
+    // same time, makes sure the SurfaceFlinger progresses one frame
+    // after the transaction closes. The results of the transaction
+    // should be available in the latest frame stored by the fake
+    // composer.
+    {
+        GlobalTransactionScope gts(*sFakeComposer);
+        ASSERT_EQ(NO_ERROR, mFGSurfaceControl->setPosition(128, 128));
+        // NOTE: No changes yet, so vsync will do nothing, HWC does not get any calls.
+        // (How to verify that? Throw in vsync and wait a 2x frame time? Separate test?)
+        //
+        // sFakeComposer->runVSyncAndWait();
+    }
+
+    fillSurfaceRGBA8(mFGSurfaceControl, GREEN);
+    sFakeComposer->runVSyncAndWait();
+
+    ASSERT_EQ(3, sFakeComposer->getFrameCount()); // Make sure the waits didn't time out and there's
+                                                  // no extra frames.
+
+    // NOTE: Frame 0 is produced in the SetUp.
+    auto frame1Ref = mBaseFrame;
+    frame1Ref[FG_LAYER].mDisplayFrame =
+            hwc_rect_t{128, 128, 128 + 64, 128 + 64}; // Top-most layer moves.
+    EXPECT_TRUE(framesAreSame(frame1Ref, sFakeComposer->getFrameRects(1)));
+
+    auto frame2Ref = frame1Ref;
+    frame2Ref[FG_LAYER].mSwapCount++;
+    EXPECT_TRUE(framesAreSame(frame2Ref, sFakeComposer->getFrameRects(2)));
+}
+
+TEST_F(TransactionTest, LayerResize) {
+    ALOGD("TransactionTest::LayerResize");
+    {
+        GlobalTransactionScope gts(*sFakeComposer);
+        ASSERT_EQ(NO_ERROR, mFGSurfaceControl->setSize(128, 128));
+    }
+
+    fillSurfaceRGBA8(mFGSurfaceControl, GREEN);
+    sFakeComposer->runVSyncAndWait();
+
+    ASSERT_EQ(3, sFakeComposer->getFrameCount()); // Make sure the waits didn't time out and there's
+                                                  // no extra frames.
+
+    auto frame1Ref = mBaseFrame;
+    // NOTE: The resize should not be visible for frame 1 as there's no buffer with new size posted.
+    EXPECT_TRUE(framesAreSame(frame1Ref, sFakeComposer->getFrameRects(1)));
+
+    auto frame2Ref = frame1Ref;
+    frame2Ref[FG_LAYER].mSwapCount++;
+    frame2Ref[FG_LAYER].mDisplayFrame = hwc_rect_t{64, 64, 64 + 128, 64 + 128};
+    frame2Ref[FG_LAYER].mSourceCrop = hwc_frect_t{0.f, 0.f, 128.f, 128.f};
+    EXPECT_TRUE(framesAreSame(frame2Ref, sFakeComposer->getFrameRects(2)));
+}
+
+TEST_F(TransactionTest, LayerCrop) {
+    // TODO: Add scaling to confirm that crop happens in buffer space?
+    {
+        GlobalTransactionScope gts(*sFakeComposer);
+        Rect cropRect(16, 16, 32, 32);
+        ASSERT_EQ(NO_ERROR, mFGSurfaceControl->setCrop(cropRect));
+    }
+    ASSERT_EQ(2, sFakeComposer->getFrameCount());
+
+    auto referenceFrame = mBaseFrame;
+    referenceFrame[FG_LAYER].mSourceCrop = hwc_frect_t{16.f, 16.f, 32.f, 32.f};
+    referenceFrame[FG_LAYER].mDisplayFrame = hwc_rect_t{64 + 16, 64 + 16, 64 + 32, 64 + 32};
+    EXPECT_TRUE(framesAreSame(referenceFrame, sFakeComposer->getLatestFrame()));
+}
+
+TEST_F(TransactionTest, LayerFinalCrop) {
+    // TODO: Add scaling to confirm that crop happens in display space?
+    {
+        GlobalTransactionScope gts(*sFakeComposer);
+        Rect cropRect(32, 32, 32 + 64, 32 + 64);
+        ASSERT_EQ(NO_ERROR, mFGSurfaceControl->setFinalCrop(cropRect));
+    }
+    ASSERT_EQ(2, sFakeComposer->getFrameCount());
+
+    // In display space we are cropping with [32, 32, 96, 96] against display rect
+    // [64, 64, 128, 128]. Should yield display rect [64, 64, 96, 96]
+    auto referenceFrame = mBaseFrame;
+    referenceFrame[FG_LAYER].mSourceCrop = hwc_frect_t{0.f, 0.f, 32.f, 32.f};
+    referenceFrame[FG_LAYER].mDisplayFrame = hwc_rect_t{64, 64, 64 + 32, 64 + 32};
+
+    EXPECT_TRUE(framesAreSame(referenceFrame, sFakeComposer->getLatestFrame()));
+}
+
+TEST_F(TransactionTest, LayerFinalCropEmpty) {
+    // TODO: Add scaling to confirm that crop happens in display space?
+    {
+        GlobalTransactionScope gts(*sFakeComposer);
+        Rect cropRect(16, 16, 32, 32);
+        ASSERT_EQ(NO_ERROR, mFGSurfaceControl->setFinalCrop(cropRect));
+    }
+    ASSERT_EQ(2, sFakeComposer->getFrameCount());
+
+    // In display space we are cropping with [16, 16, 32, 32] against display rect
+    // [64, 64, 128, 128]. The intersection is empty and only the background layer is composited.
+    std::vector<RenderState> referenceFrame(1);
+    referenceFrame[BG_LAYER] = mBaseFrame[BG_LAYER];
+    EXPECT_TRUE(framesAreSame(referenceFrame, sFakeComposer->getLatestFrame()));
+}
+
+TEST_F(TransactionTest, LayerSetLayer) {
+    {
+        GlobalTransactionScope gts(*sFakeComposer);
+        ASSERT_EQ(NO_ERROR, mFGSurfaceControl->setLayer(INT_MAX - 3));
+    }
+    ASSERT_EQ(2, sFakeComposer->getFrameCount());
+
+    // The layers will switch order, but both are rendered because the background layer is
+    // transparent (RGBA8888).
+    std::vector<RenderState> referenceFrame(2);
+    referenceFrame[0] = mBaseFrame[FG_LAYER];
+    referenceFrame[1] = mBaseFrame[BG_LAYER];
+    EXPECT_TRUE(framesAreSame(referenceFrame, sFakeComposer->getLatestFrame()));
+}
+
+TEST_F(TransactionTest, LayerSetLayerOpaque) {
+    {
+        GlobalTransactionScope gts(*sFakeComposer);
+        ASSERT_EQ(NO_ERROR, mFGSurfaceControl->setLayer(INT_MAX - 3));
+        ASSERT_EQ(NO_ERROR,
+                  mBGSurfaceControl->setFlags(layer_state_t::eLayerOpaque,
+                                              layer_state_t::eLayerOpaque));
+    }
+    ASSERT_EQ(2, sFakeComposer->getFrameCount());
+
+    // The former foreground layer is now covered with opaque layer - it should have disappeared
+    std::vector<RenderState> referenceFrame(1);
+    referenceFrame[BG_LAYER] = mBaseFrame[BG_LAYER];
+    EXPECT_TRUE(framesAreSame(referenceFrame, sFakeComposer->getLatestFrame()));
+}
+
+TEST_F(TransactionTest, SetLayerStack) {
+    ALOGD("TransactionTest::SetLayerStack");
+    {
+        GlobalTransactionScope gts(*sFakeComposer);
+        ASSERT_EQ(NO_ERROR, mFGSurfaceControl->setLayerStack(1));
+    }
+
+    // Foreground layer should have disappeared.
+    ASSERT_EQ(2, sFakeComposer->getFrameCount());
+    std::vector<RenderState> refFrame(1);
+    refFrame[BG_LAYER] = mBaseFrame[BG_LAYER];
+    EXPECT_TRUE(framesAreSame(refFrame, sFakeComposer->getLatestFrame()));
+}
+
+TEST_F(TransactionTest, LayerShowHide) {
+    ALOGD("TransactionTest::LayerShowHide");
+    {
+        GlobalTransactionScope gts(*sFakeComposer);
+        ASSERT_EQ(NO_ERROR, mFGSurfaceControl->hide());
+    }
+
+    // Foreground layer should have disappeared.
+    ASSERT_EQ(2, sFakeComposer->getFrameCount());
+    std::vector<RenderState> refFrame(1);
+    refFrame[BG_LAYER] = mBaseFrame[BG_LAYER];
+    EXPECT_TRUE(framesAreSame(refFrame, sFakeComposer->getLatestFrame()));
+
+    {
+        GlobalTransactionScope gts(*sFakeComposer);
+        ASSERT_EQ(NO_ERROR, mFGSurfaceControl->show());
+    }
+
+    // Foreground layer should be back
+    ASSERT_EQ(3, sFakeComposer->getFrameCount());
+    EXPECT_TRUE(framesAreSame(mBaseFrame, sFakeComposer->getLatestFrame()));
+}
+
+TEST_F(TransactionTest, LayerSetAlpha) {
+    {
+        GlobalTransactionScope gts(*sFakeComposer);
+        ASSERT_EQ(NO_ERROR, mFGSurfaceControl->setAlpha(0.75f));
+    }
+
+    ASSERT_EQ(2, sFakeComposer->getFrameCount());
+    auto referenceFrame = mBaseFrame;
+    referenceFrame[FG_LAYER].mPlaneAlpha = 0.75f;
+    EXPECT_TRUE(framesAreSame(referenceFrame, sFakeComposer->getLatestFrame()));
+}
+
+TEST_F(TransactionTest, LayerSetFlags) {
+    {
+        GlobalTransactionScope gts(*sFakeComposer);
+        ASSERT_EQ(NO_ERROR,
+                  mFGSurfaceControl->setFlags(layer_state_t::eLayerHidden,
+                                              layer_state_t::eLayerHidden));
+    }
+
+    // Foreground layer should have disappeared.
+    ASSERT_EQ(2, sFakeComposer->getFrameCount());
+    std::vector<RenderState> refFrame(1);
+    refFrame[BG_LAYER] = mBaseFrame[BG_LAYER];
+    EXPECT_TRUE(framesAreSame(refFrame, sFakeComposer->getLatestFrame()));
+}
+
+TEST_F(TransactionTest, LayerSetMatrix) {
+    struct matrixTestData {
+        float matrix[4];
+        hwc_transform_t expectedTransform;
+        hwc_rect_t expectedDisplayFrame;
+    };
+
+    // The matrix operates on the display frame and is applied before
+    // the position is added. So, the foreground layer rect is (0, 0,
+    // 64, 64) is first transformed, potentially yielding negative
+    // coordinates and then the position (64, 64) is added yielding
+    // the final on-screen rectangles given.
+
+    const matrixTestData MATRIX_TESTS[7] = // clang-format off
+            {{{-1.f, 0.f, 0.f, 1.f},    HWC_TRANSFORM_FLIP_H,           {0, 64, 64, 128}},
+             {{1.f, 0.f, 0.f, -1.f},    HWC_TRANSFORM_FLIP_V,           {64, 0, 128, 64}},
+             {{0.f, 1.f, -1.f, 0.f},    HWC_TRANSFORM_ROT_90,           {0, 64, 64, 128}},
+             {{-1.f, 0.f, 0.f, -1.f},   HWC_TRANSFORM_ROT_180,          {0, 0, 64, 64}},
+             {{0.f, -1.f, 1.f, 0.f},    HWC_TRANSFORM_ROT_270,          {64, 0, 128, 64}},
+             {{0.f, 1.f, 1.f, 0.f},     HWC_TRANSFORM_FLIP_H_ROT_90,    {64, 64, 128, 128}},
+             {{0.f, 1.f, 1.f, 0.f},     HWC_TRANSFORM_FLIP_V_ROT_90,    {64, 64, 128, 128}}};
+    // clang-format on
+    constexpr int TEST_COUNT = sizeof(MATRIX_TESTS)/sizeof(matrixTestData);
+
+    for (int i = 0; i < TEST_COUNT; i++) {
+        // TODO: How to leverage the HWC2 stringifiers?
+        const matrixTestData& xform = MATRIX_TESTS[i];
+        SCOPED_TRACE(i);
+        {
+            GlobalTransactionScope gts(*sFakeComposer);
+            ASSERT_EQ(NO_ERROR,
+                      mFGSurfaceControl->setMatrix(xform.matrix[0], xform.matrix[1],
+                                                   xform.matrix[2], xform.matrix[3]));
+        }
+
+        auto referenceFrame = mBaseFrame;
+        referenceFrame[FG_LAYER].mTransform = xform.expectedTransform;
+        referenceFrame[FG_LAYER].mDisplayFrame = xform.expectedDisplayFrame;
+
+        EXPECT_TRUE(framesAreSame(referenceFrame, sFakeComposer->getLatestFrame()));
+    }
+}
+
+#if 0
+TEST_F(TransactionTest, LayerSetMatrix2) {
+    {
+        GlobalTransactionScope gts(*sFakeComposer);
+        // TODO: PLEASE SPEC THE FUNCTION!
+        ASSERT_EQ(NO_ERROR, mFGSurfaceControl->setMatrix(0.11f, 0.123f,
+                                                         -2.33f, 0.22f));
+    }
+    auto referenceFrame = mBaseFrame;
+    // TODO: Is this correct for sure?
+    //referenceFrame[FG_LAYER].mTransform = HWC_TRANSFORM_FLIP_V & HWC_TRANSFORM_ROT_90;
+
+    EXPECT_TRUE(framesAreSame(referenceFrame, sFakeComposer->getLatestFrame()));
+}
+#endif
+
+TEST_F(TransactionTest, DeferredTransaction) {
+    // Synchronization surface
+    constexpr static int SYNC_LAYER = 2;
+    auto syncSurfaceControl = mComposerClient->createSurface(String8("Sync Test Surface"), 1, 1,
+                                                             PIXEL_FORMAT_RGBA_8888, 0);
+    ASSERT_TRUE(syncSurfaceControl != nullptr);
+    ASSERT_TRUE(syncSurfaceControl->isValid());
+
+    fillSurfaceRGBA8(syncSurfaceControl, DARK_GRAY);
+
+    {
+        GlobalTransactionScope gts(*sFakeComposer);
+        ASSERT_EQ(NO_ERROR, syncSurfaceControl->setLayer(INT32_MAX - 1));
+        ASSERT_EQ(NO_ERROR, syncSurfaceControl->setPosition(mDisplayWidth - 2, mDisplayHeight - 2));
+        ASSERT_EQ(NO_ERROR, syncSurfaceControl->show());
+    }
+    auto referenceFrame = mBaseFrame;
+    referenceFrame.push_back(makeSimpleRect(mDisplayWidth - 2, mDisplayHeight - 2,
+                                            mDisplayWidth - 1, mDisplayHeight - 1));
+    referenceFrame[SYNC_LAYER].mSwapCount = 1;
+    EXPECT_EQ(2, sFakeComposer->getFrameCount());
+    EXPECT_TRUE(framesAreSame(referenceFrame, sFakeComposer->getLatestFrame()));
+
+    // set up two deferred transactions on different frames - these should not yield composited
+    // frames
+    {
+        GlobalTransactionScope gts(*sFakeComposer);
+        ASSERT_EQ(NO_ERROR, mFGSurfaceControl->setAlpha(0.75));
+        mFGSurfaceControl
+                ->deferTransactionUntil(syncSurfaceControl->getHandle(),
+                                        syncSurfaceControl->getSurface()->getNextFrameNumber());
+    }
+    EXPECT_TRUE(framesAreSame(referenceFrame, sFakeComposer->getLatestFrame()));
+
+    {
+        GlobalTransactionScope gts(*sFakeComposer);
+        ASSERT_EQ(NO_ERROR, mFGSurfaceControl->setPosition(128, 128));
+        mFGSurfaceControl
+                ->deferTransactionUntil(syncSurfaceControl->getHandle(),
+                                        syncSurfaceControl->getSurface()->getNextFrameNumber() + 1);
+    }
+    EXPECT_EQ(4, sFakeComposer->getFrameCount());
+    EXPECT_TRUE(framesAreSame(referenceFrame, sFakeComposer->getLatestFrame()));
+
+    // should trigger the first deferred transaction, but not the second one
+    fillSurfaceRGBA8(syncSurfaceControl, DARK_GRAY);
+    sFakeComposer->runVSyncAndWait();
+    EXPECT_EQ(5, sFakeComposer->getFrameCount());
+
+    referenceFrame[FG_LAYER].mPlaneAlpha = 0.75f;
+    referenceFrame[SYNC_LAYER].mSwapCount++;
+    EXPECT_TRUE(framesAreSame(referenceFrame, sFakeComposer->getLatestFrame()));
+
+    // should show up immediately since it's not deferred
+    {
+        GlobalTransactionScope gts(*sFakeComposer);
+        ASSERT_EQ(NO_ERROR, mFGSurfaceControl->setAlpha(1.0));
+    }
+    referenceFrame[FG_LAYER].mPlaneAlpha = 1.f;
+    EXPECT_EQ(6, sFakeComposer->getFrameCount());
+    EXPECT_TRUE(framesAreSame(referenceFrame, sFakeComposer->getLatestFrame()));
+
+    // trigger the second deferred transaction
+    fillSurfaceRGBA8(syncSurfaceControl, DARK_GRAY);
+    sFakeComposer->runVSyncAndWait();
+    // TODO: Compute from layer size?
+    referenceFrame[FG_LAYER].mDisplayFrame = hwc_rect_t{128, 128, 128 + 64, 128 + 64};
+    referenceFrame[SYNC_LAYER].mSwapCount++;
+    EXPECT_EQ(7, sFakeComposer->getFrameCount());
+    EXPECT_TRUE(framesAreSame(referenceFrame, sFakeComposer->getLatestFrame()));
+}
+
+TEST_F(TransactionTest, SetRelativeLayer) {
+    constexpr int RELATIVE_LAYER = 2;
+    auto relativeSurfaceControl = mComposerClient->createSurface(String8("Test Surface"), 64, 64,
+                                                                 PIXEL_FORMAT_RGBA_8888, 0);
+    fillSurfaceRGBA8(relativeSurfaceControl, LIGHT_RED);
+
+    // Now we stack the surface above the foreground surface and make sure it is visible.
+    {
+        GlobalTransactionScope gts(*sFakeComposer);
+        relativeSurfaceControl->setPosition(64, 64);
+        relativeSurfaceControl->show();
+        relativeSurfaceControl->setRelativeLayer(mFGSurfaceControl->getHandle(), 1);
+    }
+    auto referenceFrame = mBaseFrame;
+    // NOTE: All three layers will be visible as the surfaces are
+    // transparent because of the RGBA format.
+    referenceFrame.push_back(makeSimpleRect(64, 64, 64 + 64, 64 + 64));
+    referenceFrame[RELATIVE_LAYER].mSwapCount = 1;
+    EXPECT_TRUE(framesAreSame(referenceFrame, sFakeComposer->getLatestFrame()));
+
+    // A call to setLayer will override a call to setRelativeLayer
+    {
+        GlobalTransactionScope gts(*sFakeComposer);
+        relativeSurfaceControl->setLayer(0);
+    }
+
+    // Previous top layer will now appear at the bottom.
+    auto referenceFrame2 = mBaseFrame;
+    referenceFrame2.insert(referenceFrame2.begin(), referenceFrame[RELATIVE_LAYER]);
+    EXPECT_EQ(3, sFakeComposer->getFrameCount());
+    EXPECT_TRUE(framesAreSame(referenceFrame2, sFakeComposer->getLatestFrame()));
+}
+
+class ChildLayerTest : public TransactionTest {
+protected:
+    constexpr static int CHILD_LAYER = 2;
+
+    void SetUp() override {
+        TransactionTest::SetUp();
+        mChild = mComposerClient->createSurface(String8("Child surface"), 10, 10,
+                                                PIXEL_FORMAT_RGBA_8888, 0, mFGSurfaceControl.get());
+        fillSurfaceRGBA8(mChild, LIGHT_GRAY);
+
+        sFakeComposer->runVSyncAndWait();
+        mBaseFrame.push_back(makeSimpleRect(64, 64, 64 + 10, 64 + 10));
+        mBaseFrame[CHILD_LAYER].mSwapCount = 1;
+        ASSERT_EQ(2, sFakeComposer->getFrameCount());
+        ASSERT_TRUE(framesAreSame(mBaseFrame, sFakeComposer->getLatestFrame()));
+    }
+    void TearDown() override {
+        mChild = 0;
+        TransactionTest::TearDown();
+    }
+
+    sp<SurfaceControl> mChild;
+};
+
+TEST_F(ChildLayerTest, Positioning) {
+    {
+        GlobalTransactionScope gts(*sFakeComposer);
+        mChild->show();
+        mChild->setPosition(10, 10);
+        // Move to the same position as in the original setup.
+        mFGSurfaceControl->setPosition(64, 64);
+    }
+
+    auto referenceFrame = mBaseFrame;
+    referenceFrame[FG_LAYER].mDisplayFrame = hwc_rect_t{64, 64, 64 + 64, 64 + 64};
+    referenceFrame[CHILD_LAYER].mDisplayFrame =
+            hwc_rect_t{64 + 10, 64 + 10, 64 + 10 + 10, 64 + 10 + 10};
+    EXPECT_TRUE(framesAreSame(referenceFrame, sFakeComposer->getLatestFrame()));
+
+    {
+        GlobalTransactionScope gts(*sFakeComposer);
+        ASSERT_EQ(NO_ERROR, mFGSurfaceControl->setPosition(0, 0));
+    }
+
+    auto referenceFrame2 = mBaseFrame;
+    referenceFrame2[FG_LAYER].mDisplayFrame = hwc_rect_t{0, 0, 0 + 64, 0 + 64};
+    referenceFrame2[CHILD_LAYER].mDisplayFrame =
+            hwc_rect_t{0 + 10, 0 + 10, 0 + 10 + 10, 0 + 10 + 10};
+    EXPECT_TRUE(framesAreSame(referenceFrame2, sFakeComposer->getLatestFrame()));
+}
+
+TEST_F(ChildLayerTest, Cropping) {
+    {
+        GlobalTransactionScope gts(*sFakeComposer);
+        mChild->show();
+        mChild->setPosition(0, 0);
+        mFGSurfaceControl->setPosition(0, 0);
+        mFGSurfaceControl->setCrop(Rect(0, 0, 5, 5));
+    }
+    // NOTE: The foreground surface would be occluded by the child
+    // now, but is included in the stack because the child is
+    // transparent.
+    auto referenceFrame = mBaseFrame;
+    referenceFrame[FG_LAYER].mDisplayFrame = hwc_rect_t{0, 0, 0 + 5, 0 + 5};
+    referenceFrame[FG_LAYER].mSourceCrop = hwc_frect_t{0.f, 0.f, 5.f, 5.f};
+    referenceFrame[CHILD_LAYER].mDisplayFrame = hwc_rect_t{0, 0, 0 + 5, 0 + 5};
+    referenceFrame[CHILD_LAYER].mSourceCrop = hwc_frect_t{0.f, 0.f, 5.f, 5.f};
+    EXPECT_TRUE(framesAreSame(referenceFrame, sFakeComposer->getLatestFrame()));
+}
+
+TEST_F(ChildLayerTest, FinalCropping) {
+    {
+        GlobalTransactionScope gts(*sFakeComposer);
+        mChild->show();
+        mChild->setPosition(0, 0);
+        mFGSurfaceControl->setPosition(0, 0);
+        mFGSurfaceControl->setFinalCrop(Rect(0, 0, 5, 5));
+    }
+    auto referenceFrame = mBaseFrame;
+    referenceFrame[FG_LAYER].mDisplayFrame = hwc_rect_t{0, 0, 0 + 5, 0 + 5};
+    referenceFrame[FG_LAYER].mSourceCrop = hwc_frect_t{0.f, 0.f, 5.f, 5.f};
+    referenceFrame[CHILD_LAYER].mDisplayFrame = hwc_rect_t{0, 0, 0 + 5, 0 + 5};
+    referenceFrame[CHILD_LAYER].mSourceCrop = hwc_frect_t{0.f, 0.f, 5.f, 5.f};
+    EXPECT_TRUE(framesAreSame(referenceFrame, sFakeComposer->getLatestFrame()));
+}
+
+TEST_F(ChildLayerTest, Constraints) {
+    {
+        GlobalTransactionScope gts(*sFakeComposer);
+        mChild->show();
+        mFGSurfaceControl->setPosition(0, 0);
+        mChild->setPosition(63, 63);
+    }
+    auto referenceFrame = mBaseFrame;
+    referenceFrame[FG_LAYER].mDisplayFrame = hwc_rect_t{0, 0, 64, 64};
+    referenceFrame[CHILD_LAYER].mDisplayFrame = hwc_rect_t{63, 63, 64, 64};
+    referenceFrame[CHILD_LAYER].mSourceCrop = hwc_frect_t{0.f, 0.f, 1.f, 1.f};
+    EXPECT_TRUE(framesAreSame(referenceFrame, sFakeComposer->getLatestFrame()));
+}
+
+TEST_F(ChildLayerTest, Scaling) {
+    {
+        GlobalTransactionScope gts(*sFakeComposer);
+        mFGSurfaceControl->setPosition(0, 0);
+    }
+    auto referenceFrame = mBaseFrame;
+    referenceFrame[FG_LAYER].mDisplayFrame = hwc_rect_t{0, 0, 64, 64};
+    referenceFrame[CHILD_LAYER].mDisplayFrame = hwc_rect_t{0, 0, 10, 10};
+    EXPECT_TRUE(framesAreSame(referenceFrame, sFakeComposer->getLatestFrame()));
+
+    {
+        GlobalTransactionScope gts(*sFakeComposer);
+        mFGSurfaceControl->setMatrix(2.0, 0, 0, 2.0);
+    }
+
+    auto referenceFrame2 = mBaseFrame;
+    referenceFrame2[FG_LAYER].mDisplayFrame = hwc_rect_t{0, 0, 128, 128};
+    referenceFrame2[CHILD_LAYER].mDisplayFrame = hwc_rect_t{0, 0, 20, 20};
+    EXPECT_TRUE(framesAreSame(referenceFrame2, sFakeComposer->getLatestFrame()));
+}
+
+TEST_F(ChildLayerTest, LayerAlpha) {
+    {
+        GlobalTransactionScope gts(*sFakeComposer);
+        mChild->show();
+        mChild->setPosition(0, 0);
+        mFGSurfaceControl->setPosition(0, 0);
+        ASSERT_EQ(NO_ERROR, mChild->setAlpha(0.5));
+    }
+
+    auto referenceFrame = mBaseFrame;
+    referenceFrame[FG_LAYER].mDisplayFrame = hwc_rect_t{0, 0, 64, 64};
+    referenceFrame[CHILD_LAYER].mDisplayFrame = hwc_rect_t{0, 0, 10, 10};
+    referenceFrame[CHILD_LAYER].mPlaneAlpha = 0.5f;
+    EXPECT_TRUE(framesAreSame(referenceFrame, sFakeComposer->getLatestFrame()));
+
+    {
+        GlobalTransactionScope gts(*sFakeComposer);
+        ASSERT_EQ(NO_ERROR, mFGSurfaceControl->setAlpha(0.5));
+    }
+
+    auto referenceFrame2 = referenceFrame;
+    referenceFrame2[FG_LAYER].mPlaneAlpha = 0.5f;
+    referenceFrame2[CHILD_LAYER].mPlaneAlpha = 0.25f;
+    EXPECT_TRUE(framesAreSame(referenceFrame2, sFakeComposer->getLatestFrame()));
+}
+
+TEST_F(ChildLayerTest, ReparentChildren) {
+    {
+        GlobalTransactionScope gts(*sFakeComposer);
+        mChild->show();
+        mChild->setPosition(10, 10);
+        mFGSurfaceControl->setPosition(64, 64);
+    }
+    auto referenceFrame = mBaseFrame;
+    referenceFrame[FG_LAYER].mDisplayFrame = hwc_rect_t{64, 64, 64 + 64, 64 + 64};
+    referenceFrame[CHILD_LAYER].mDisplayFrame =
+            hwc_rect_t{64 + 10, 64 + 10, 64 + 10 + 10, 64 + 10 + 10};
+    EXPECT_TRUE(framesAreSame(referenceFrame, sFakeComposer->getLatestFrame()));
+
+    {
+        GlobalTransactionScope gts(*sFakeComposer);
+        mFGSurfaceControl->reparentChildren(mBGSurfaceControl->getHandle());
+    }
+
+    auto referenceFrame2 = referenceFrame;
+    referenceFrame2[FG_LAYER].mDisplayFrame = hwc_rect_t{64, 64, 64 + 64, 64 + 64};
+    referenceFrame2[CHILD_LAYER].mDisplayFrame = hwc_rect_t{10, 10, 10 + 10, 10 + 10};
+    EXPECT_TRUE(framesAreSame(referenceFrame2, sFakeComposer->getLatestFrame()));
+}
+
+TEST_F(ChildLayerTest, DetachChildren) {
+    {
+        GlobalTransactionScope gts(*sFakeComposer);
+        mChild->show();
+        mChild->setPosition(10, 10);
+        mFGSurfaceControl->setPosition(64, 64);
+    }
+
+    auto referenceFrame = mBaseFrame;
+    referenceFrame[FG_LAYER].mDisplayFrame = hwc_rect_t{64, 64, 64 + 64, 64 + 64};
+    referenceFrame[CHILD_LAYER].mDisplayFrame =
+            hwc_rect_t{64 + 10, 64 + 10, 64 + 10 + 10, 64 + 10 + 10};
+    EXPECT_TRUE(framesAreSame(referenceFrame, sFakeComposer->getLatestFrame()));
+
+    {
+        GlobalTransactionScope gts(*sFakeComposer);
+        mFGSurfaceControl->detachChildren();
+    }
+
+    {
+        GlobalTransactionScope gts(*sFakeComposer);
+        mChild->hide();
+    }
+
+    // Nothing should have changed. The child control becomes a no-op
+    // zombie on detach. See comments for detachChildren in the
+    // SurfaceControl.h file.
+    EXPECT_TRUE(framesAreSame(referenceFrame, sFakeComposer->getLatestFrame()));
+}
+
+TEST_F(ChildLayerTest, InheritNonTransformScalingFromParent) {
+    {
+        GlobalTransactionScope gts(*sFakeComposer);
+        mChild->show();
+        mChild->setPosition(0, 0);
+        mFGSurfaceControl->setPosition(0, 0);
+    }
+
+    {
+        GlobalTransactionScope gts(*sFakeComposer);
+        mFGSurfaceControl->setOverrideScalingMode(NATIVE_WINDOW_SCALING_MODE_SCALE_TO_WINDOW);
+        // We cause scaling by 2.
+        mFGSurfaceControl->setSize(128, 128);
+    }
+
+    auto referenceFrame = mBaseFrame;
+    referenceFrame[FG_LAYER].mDisplayFrame = hwc_rect_t{0, 0, 128, 128};
+    referenceFrame[FG_LAYER].mSourceCrop = hwc_frect_t{0.f, 0.f, 64.f, 64.f};
+    referenceFrame[CHILD_LAYER].mDisplayFrame = hwc_rect_t{0, 0, 20, 20};
+    referenceFrame[CHILD_LAYER].mSourceCrop = hwc_frect_t{0.f, 0.f, 10.f, 10.f};
+    EXPECT_TRUE(framesAreSame(referenceFrame, sFakeComposer->getLatestFrame()));
+}
+
+// Regression test for b/37673612
+TEST_F(ChildLayerTest, ChildrenWithParentBufferTransform) {
+    {
+        GlobalTransactionScope gts(*sFakeComposer);
+        mChild->show();
+        mChild->setPosition(0, 0);
+        mFGSurfaceControl->setPosition(0, 0);
+    }
+
+    // We set things up as in b/37673612 so that there is a mismatch between the buffer size and
+    // the WM specified state size.
+    {
+        GlobalTransactionScope gts(*sFakeComposer);
+        mFGSurfaceControl->setSize(128, 64);
+    }
+
+    sp<Surface> s = mFGSurfaceControl->getSurface();
+    auto anw = static_cast<ANativeWindow*>(s.get());
+    native_window_set_buffers_transform(anw, NATIVE_WINDOW_TRANSFORM_ROT_90);
+    native_window_set_buffers_dimensions(anw, 64, 128);
+    fillSurfaceRGBA8(mFGSurfaceControl, RED);
+    sFakeComposer->runVSyncAndWait();
+
+    // The child should still be in the same place and not have any strange scaling as in
+    // b/37673612.
+    auto referenceFrame = mBaseFrame;
+    referenceFrame[FG_LAYER].mDisplayFrame = hwc_rect_t{0, 0, 128, 64};
+    referenceFrame[FG_LAYER].mSourceCrop = hwc_frect_t{0.f, 0.f, 64.f, 128.f};
+    referenceFrame[FG_LAYER].mSwapCount++;
+    referenceFrame[CHILD_LAYER].mDisplayFrame = hwc_rect_t{0, 0, 10, 10};
+    EXPECT_TRUE(framesAreSame(referenceFrame, sFakeComposer->getLatestFrame()));
+}
+
+TEST_F(ChildLayerTest, Bug36858924) {
+    // Destroy the child layer
+    mChild.clear();
+
+    // Now recreate it as hidden
+    mChild = mComposerClient->createSurface(String8("Child surface"), 10, 10,
+                                            PIXEL_FORMAT_RGBA_8888, ISurfaceComposerClient::eHidden,
+                                            mFGSurfaceControl.get());
+
+    // Show the child layer in a deferred transaction
+    {
+        GlobalTransactionScope gts(*sFakeComposer);
+        mChild->deferTransactionUntil(mFGSurfaceControl->getHandle(),
+                                      mFGSurfaceControl->getSurface()->getNextFrameNumber());
+        mChild->show();
+    }
+
+    // Render the foreground surface a few times
+    //
+    // Prior to the bugfix for b/36858924, this would usually hang while trying to fill the third
+    // frame because SurfaceFlinger would never process the deferred transaction and would therefore
+    // never acquire/release the first buffer
+    ALOGI("Filling 1");
+    fillSurfaceRGBA8(mFGSurfaceControl, GREEN);
+    sFakeComposer->runVSyncAndWait();
+    ALOGI("Filling 2");
+    fillSurfaceRGBA8(mFGSurfaceControl, BLUE);
+    sFakeComposer->runVSyncAndWait();
+    ALOGI("Filling 3");
+    fillSurfaceRGBA8(mFGSurfaceControl, RED);
+    sFakeComposer->runVSyncAndWait();
+    ALOGI("Filling 4");
+    fillSurfaceRGBA8(mFGSurfaceControl, GREEN);
+    sFakeComposer->runVSyncAndWait();
+}
+
+class LatchingTest : public TransactionTest {
+protected:
+    void lockAndFillFGBuffer() { fillSurfaceRGBA8(mFGSurfaceControl, RED, false); }
+
+    void unlockFGBuffer() {
+        sp<Surface> s = mFGSurfaceControl->getSurface();
+        ASSERT_EQ(NO_ERROR, s->unlockAndPost());
+        sFakeComposer->runVSyncAndWait();
+    }
+
+    void completeFGResize() {
+        fillSurfaceRGBA8(mFGSurfaceControl, RED);
+        sFakeComposer->runVSyncAndWait();
+    }
+    void restoreInitialState() {
+        GlobalTransactionScope gts(*sFakeComposer);
+        mFGSurfaceControl->setSize(64, 64);
+        mFGSurfaceControl->setPosition(64, 64);
+        mFGSurfaceControl->setCrop(Rect(0, 0, 64, 64));
+        mFGSurfaceControl->setFinalCrop(Rect(0, 0, -1, -1));
+    }
+};
+
+TEST_F(LatchingTest, SurfacePositionLatching) {
+    // By default position can be updated even while
+    // a resize is pending.
+    {
+        GlobalTransactionScope gts(*sFakeComposer);
+        mFGSurfaceControl->setSize(32, 32);
+        mFGSurfaceControl->setPosition(100, 100);
+    }
+
+    // The size should not have updated as we have not provided a new buffer.
+    auto referenceFrame1 = mBaseFrame;
+    referenceFrame1[FG_LAYER].mDisplayFrame = hwc_rect_t{100, 100, 100 + 64, 100 + 64};
+    EXPECT_TRUE(framesAreSame(referenceFrame1, sFakeComposer->getLatestFrame()));
+
+    restoreInitialState();
+
+    // Now we repeat with setGeometryAppliesWithResize
+    // and verify the position DOESN'T latch.
+    {
+        GlobalTransactionScope gts(*sFakeComposer);
+        mFGSurfaceControl->setGeometryAppliesWithResize();
+        mFGSurfaceControl->setSize(32, 32);
+        mFGSurfaceControl->setPosition(100, 100);
+    }
+    EXPECT_TRUE(framesAreSame(mBaseFrame, sFakeComposer->getLatestFrame()));
+
+    completeFGResize();
+
+    auto referenceFrame2 = mBaseFrame;
+    referenceFrame2[FG_LAYER].mDisplayFrame = hwc_rect_t{100, 100, 100 + 32, 100 + 32};
+    referenceFrame2[FG_LAYER].mSourceCrop = hwc_frect_t{0.f, 0.f, 32.f, 32.f};
+    referenceFrame2[FG_LAYER].mSwapCount++;
+    EXPECT_TRUE(framesAreSame(referenceFrame2, sFakeComposer->getLatestFrame()));
+}
+
+TEST_F(LatchingTest, CropLatching) {
+    // Normally the crop applies immediately even while a resize is pending.
+    {
+        GlobalTransactionScope gts(*sFakeComposer);
+        mFGSurfaceControl->setSize(128, 128);
+        mFGSurfaceControl->setCrop(Rect(0, 0, 63, 63));
+    }
+
+    auto referenceFrame1 = mBaseFrame;
+    referenceFrame1[FG_LAYER].mDisplayFrame = hwc_rect_t{64, 64, 64 + 63, 64 + 63};
+    referenceFrame1[FG_LAYER].mSourceCrop = hwc_frect_t{0.f, 0.f, 63.f, 63.f};
+    EXPECT_TRUE(framesAreSame(referenceFrame1, sFakeComposer->getLatestFrame()));
+
+    restoreInitialState();
+
+    {
+        GlobalTransactionScope gts(*sFakeComposer);
+        mFGSurfaceControl->setSize(128, 128);
+        mFGSurfaceControl->setGeometryAppliesWithResize();
+        mFGSurfaceControl->setCrop(Rect(0, 0, 63, 63));
+    }
+    EXPECT_TRUE(framesAreSame(mBaseFrame, sFakeComposer->getLatestFrame()));
+
+    completeFGResize();
+
+    auto referenceFrame2 = mBaseFrame;
+    referenceFrame2[FG_LAYER].mDisplayFrame = hwc_rect_t{64, 64, 64 + 63, 64 + 63};
+    referenceFrame2[FG_LAYER].mSourceCrop = hwc_frect_t{0.f, 0.f, 63.f, 63.f};
+    referenceFrame2[FG_LAYER].mSwapCount++;
+    EXPECT_TRUE(framesAreSame(referenceFrame2, sFakeComposer->getLatestFrame()));
+}
+
+TEST_F(LatchingTest, FinalCropLatching) {
+    // Normally the crop applies immediately even while a resize is pending.
+    {
+        GlobalTransactionScope gts(*sFakeComposer);
+        mFGSurfaceControl->setSize(128, 128);
+        mFGSurfaceControl->setFinalCrop(Rect(64, 64, 127, 127));
+    }
+
+    auto referenceFrame1 = mBaseFrame;
+    referenceFrame1[FG_LAYER].mDisplayFrame = hwc_rect_t{64, 64, 127, 127};
+    referenceFrame1[FG_LAYER].mSourceCrop =
+            hwc_frect_t{0.f, 0.f, static_cast<float>(127 - 64), static_cast<float>(127 - 64)};
+    EXPECT_TRUE(framesAreSame(referenceFrame1, sFakeComposer->getLatestFrame()));
+
+    restoreInitialState();
+
+    {
+        GlobalTransactionScope gts(*sFakeComposer);
+        mFGSurfaceControl->setSize(128, 128);
+        mFGSurfaceControl->setGeometryAppliesWithResize();
+        mFGSurfaceControl->setFinalCrop(Rect(64, 64, 127, 127));
+    }
+    EXPECT_TRUE(framesAreSame(mBaseFrame, sFakeComposer->getLatestFrame()));
+
+    completeFGResize();
+
+    auto referenceFrame2 = mBaseFrame;
+    referenceFrame2[FG_LAYER].mDisplayFrame = hwc_rect_t{64, 64, 127, 127};
+    referenceFrame2[FG_LAYER].mSourceCrop =
+            hwc_frect_t{0.f, 0.f, static_cast<float>(127 - 64), static_cast<float>(127 - 64)};
+    referenceFrame2[FG_LAYER].mSwapCount++;
+    EXPECT_TRUE(framesAreSame(referenceFrame2, sFakeComposer->getLatestFrame()));
+}
+
+// In this test we ensure that setGeometryAppliesWithResize actually demands
+// a buffer of the new size, and not just any size.
+TEST_F(LatchingTest, FinalCropLatchingBufferOldSize) {
+    // Normally the crop applies immediately even while a resize is pending.
+    {
+        GlobalTransactionScope gts(*sFakeComposer);
+        mFGSurfaceControl->setSize(128, 128);
+        mFGSurfaceControl->setFinalCrop(Rect(64, 64, 127, 127));
+    }
+
+    auto referenceFrame1 = mBaseFrame;
+    referenceFrame1[FG_LAYER].mDisplayFrame = hwc_rect_t{64, 64, 127, 127};
+    referenceFrame1[FG_LAYER].mSourceCrop =
+            hwc_frect_t{0.f, 0.f, static_cast<float>(127 - 64), static_cast<float>(127 - 64)};
+    EXPECT_TRUE(framesAreSame(referenceFrame1, sFakeComposer->getLatestFrame()));
+
+    restoreInitialState();
+
+    // In order to prepare to submit a buffer at the wrong size, we acquire it prior to
+    // initiating the resize.
+    lockAndFillFGBuffer();
+
+    {
+        GlobalTransactionScope gts(*sFakeComposer);
+        mFGSurfaceControl->setSize(128, 128);
+        mFGSurfaceControl->setGeometryAppliesWithResize();
+        mFGSurfaceControl->setFinalCrop(Rect(64, 64, 127, 127));
+    }
+    EXPECT_TRUE(framesAreSame(mBaseFrame, sFakeComposer->getLatestFrame()));
+
+    // We now submit our old buffer, at the old size, and ensure it doesn't
+    // trigger geometry latching.
+    unlockFGBuffer();
+
+    auto referenceFrame2 = mBaseFrame;
+    referenceFrame2[FG_LAYER].mSwapCount++;
+    EXPECT_TRUE(framesAreSame(referenceFrame2, sFakeComposer->getLatestFrame()));
+
+    completeFGResize();
+    auto referenceFrame3 = referenceFrame2;
+    referenceFrame3[FG_LAYER].mDisplayFrame = hwc_rect_t{64, 64, 127, 127};
+    referenceFrame3[FG_LAYER].mSourceCrop =
+            hwc_frect_t{0.f, 0.f, static_cast<float>(127 - 64), static_cast<float>(127 - 64)};
+    referenceFrame3[FG_LAYER].mSwapCount++;
+    EXPECT_TRUE(framesAreSame(referenceFrame3, sFakeComposer->getLatestFrame()));
+}
+
+TEST_F(LatchingTest, FinalCropLatchingRegressionForb37531386) {
+    // In this scenario, we attempt to set the final crop a second time while the resize
+    // is still pending, and ensure we are successful. Success meaning the second crop
+    // is the one which eventually latches and not the first.
+    {
+        GlobalTransactionScope gts(*sFakeComposer);
+        mFGSurfaceControl->setSize(128, 128);
+        mFGSurfaceControl->setGeometryAppliesWithResize();
+        mFGSurfaceControl->setFinalCrop(Rect(64, 64, 127, 127));
+    }
+
+    {
+        GlobalTransactionScope gts(*sFakeComposer);
+        mFGSurfaceControl->setFinalCrop(Rect(0, 0, -1, -1));
+    }
+    EXPECT_TRUE(framesAreSame(mBaseFrame, sFakeComposer->getLatestFrame()));
+
+    completeFGResize();
+
+    auto referenceFrame = mBaseFrame;
+    referenceFrame[FG_LAYER].mSwapCount++;
+    EXPECT_TRUE(framesAreSame(referenceFrame, sFakeComposer->getLatestFrame()));
+}
+
+} // namespace
+
+int main(int argc, char** argv) {
+    ::testing::InitGoogleTest(&argc, argv);
+
+    sftest::FakeHwcEnvironment* fakeEnvironment = new sftest::FakeHwcEnvironment;
+    ::testing::AddGlobalTestEnvironment(fakeEnvironment);
+    ::testing::InitGoogleMock(&argc, argv);
+    return RUN_ALL_TESTS();
+}
diff --git a/services/surfaceflinger/tests/hwc2/Hwc2Test.cpp b/services/surfaceflinger/tests/hwc2/Hwc2Test.cpp
index 062485e..4055527 100644
--- a/services/surfaceflinger/tests/hwc2/Hwc2Test.cpp
+++ b/services/surfaceflinger/tests/hwc2/Hwc2Test.cpp
@@ -382,7 +382,9 @@
         if (outErr) {
             *outErr = err;
         } else {
-            ASSERT_EQ(err, HWC2_ERROR_NONE) << "failed to set cursor position";
+            ASSERT_TRUE((err == HWC2_ERROR_NONE) ||
+                (err == HWC2_ERROR_BAD_LAYER)) <<
+                "failed to set cursor position";
         }
     }
 
@@ -652,7 +654,7 @@
             hwc2_layer_request_t request = requests.at(i);
 
             EXPECT_EQ(std::count(layers.begin(), layers.end(), requestedLayer),
-                    0) << "get display requests returned an unknown layer";
+                    1) << "get display requests returned an unknown layer";
             EXPECT_NE(request, 0) << "returned empty request for layer "
                     << requestedLayer;
 
@@ -1603,9 +1605,10 @@
         EXPECT_EQ(layers.size(), fences.size());
 
         for (int32_t fence : fences) {
-            EXPECT_GE(sync_wait(fence, msWait), 0);
-            if (fence >= 0)
+            if (fence >= 0) {
+                EXPECT_GE(sync_wait(fence, msWait), 0);
                 close(fence);
+            }
         }
     }
 
@@ -1643,8 +1646,9 @@
                 testLayers->getBlendMode(layer)));
         EXPECT_NO_FATAL_FAILURE(setLayerColor(display, layer,
                 testLayers->getColor(layer)));
-        EXPECT_NO_FATAL_FAILURE(setCursorPosition(display, layer, cursor.left,
-                cursor.top));
+        if (composition == HWC2_COMPOSITION_CURSOR)
+            EXPECT_NO_FATAL_FAILURE(setCursorPosition(display, layer,
+            cursor.left, cursor.top));
         EXPECT_NO_FATAL_FAILURE(setLayerDataspace(display, layer,
                 testLayers->getDataspace(layer)));
         EXPECT_NO_FATAL_FAILURE(setLayerDisplayFrame(display, layer,
@@ -2895,7 +2899,6 @@
     ASSERT_NO_FATAL_FAILURE(setLayerProperty(Hwc2TestCoverage::Complete,
             [] (Hwc2Test* test, hwc2_display_t display, hwc2_layer_t layer,
                     Hwc2TestLayer* testLayer, hwc2_error_t* outErr) {
-
                 const hwc_rect_t cursorPosition = testLayer->getCursorPosition();
                 EXPECT_NO_FATAL_FAILURE(test->setCursorPosition(display, layer,
                         cursorPosition.left, cursorPosition.top, outErr));
@@ -4406,11 +4409,11 @@
 /* TESTCASE: Tests that the HWC2 cannot destroy a physical display. */
 TEST_F(Hwc2Test, DESTROY_VIRTUAL_DISPLAY_bad_parameter)
 {
-    hwc2_display_t display = HWC_DISPLAY_PRIMARY;
     hwc2_error_t err = HWC2_ERROR_NONE;
-
-    ASSERT_NO_FATAL_FAILURE(destroyVirtualDisplay(display, &err));
-    EXPECT_EQ(err, HWC2_ERROR_BAD_PARAMETER) << "returned wrong error code";
+    for (auto display : mDisplays) {
+        ASSERT_NO_FATAL_FAILURE(destroyVirtualDisplay(display, &err));
+        EXPECT_EQ(err, HWC2_ERROR_BAD_PARAMETER) << "returned wrong error code";
+    }
 }
 
 /* TESTCASE: Tests that the HWC2 can get the max virtual display count. */
diff --git a/services/vr/hardware_composer/impl/vr_hwc.cpp b/services/vr/hardware_composer/impl/vr_hwc.cpp
index 5e32af0..fd271d0 100644
--- a/services/vr/hardware_composer/impl/vr_hwc.cpp
+++ b/services/vr/hardware_composer/impl/vr_hwc.cpp
@@ -232,7 +232,7 @@
 
 VrHwc::~VrHwc() {}
 
-bool VrHwc::hasCapability(Capability capability) const { return false; }
+bool VrHwc::hasCapability(Capability /* capability */) const { return false; }
 
 void VrHwc::removeClient() {
   std::lock_guard<std::mutex> guard(mutex_);
@@ -306,13 +306,15 @@
   return Error::NONE;
 }
 
-Error VrHwc::getClientTargetSupport(Display display, uint32_t width,
-                                    uint32_t height, PixelFormat format,
-                                    Dataspace dataspace) {
+Error VrHwc::getClientTargetSupport(Display /* display */, uint32_t /* width */,
+                                    uint32_t /* height */,
+                                    PixelFormat /* format */,
+                                    Dataspace /* dataspace */) {
   return Error::NONE;
 }
 
-Error VrHwc::getColorModes(Display display, hidl_vec<ColorMode>* outModes) {
+Error VrHwc::getColorModes(Display /* display */,
+                           hidl_vec<ColorMode>* outModes) {
   std::vector<ColorMode> color_modes(1, ColorMode::NATIVE);
   *outModes = hidl_vec<ColorMode>(color_modes);
   return Error::NONE;
@@ -379,7 +381,7 @@
   return Error::NONE;
 }
 
-Error VrHwc::getDisplayName(Display display, hidl_string* outName) {
+Error VrHwc::getDisplayName(Display /* display */, hidl_string* outName) {
   *outName = hidl_string();
   return Error::NONE;
 }
@@ -409,7 +411,8 @@
   return Error::NONE;
 }
 
-Error VrHwc::getHdrCapabilities(Display display, hidl_vec<Hdr>* outTypes,
+Error VrHwc::getHdrCapabilities(Display /* display */,
+                                hidl_vec<Hdr>* /* outTypes */,
                                 float* outMaxLuminance,
                                 float* outMaxAverageLuminance,
                                 float* outMinLuminance) {
@@ -473,8 +476,8 @@
 }
 
 Error VrHwc::setClientTarget(Display display, buffer_handle_t target,
-                             int32_t acquireFence, int32_t dataspace,
-                             const std::vector<hwc_rect_t>& damage) {
+                             int32_t acquireFence, int32_t /* dataspace */,
+                             const std::vector<hwc_rect_t>& /* damage */) {
   base::unique_fd fence(acquireFence);
   std::lock_guard<std::mutex> guard(mutex_);
   auto display_ptr = FindDisplay(display);
@@ -490,7 +493,7 @@
   return Error::NONE;
 }
 
-Error VrHwc::setOutputBuffer(Display display, buffer_handle_t buffer,
+Error VrHwc::setOutputBuffer(Display display, buffer_handle_t /* buffer */,
                              int32_t releaseFence) {
   base::unique_fd fence(releaseFence);
   std::lock_guard<std::mutex> guard(mutex_);
@@ -505,8 +508,9 @@
 Error VrHwc::validateDisplay(
     Display display, std::vector<Layer>* outChangedLayers,
     std::vector<IComposerClient::Composition>* outCompositionTypes,
-    uint32_t* outDisplayRequestMask, std::vector<Layer>* outRequestedLayers,
-    std::vector<uint32_t>* outRequestMasks) {
+    uint32_t* /* outDisplayRequestMask */,
+    std::vector<Layer>* /* outRequestedLayers */,
+    std::vector<uint32_t>* /* outRequestMasks */) {
   std::lock_guard<std::mutex> guard(mutex_);
   auto display_ptr = FindDisplay(display);
   if (!display_ptr)
@@ -517,7 +521,7 @@
   return Error::NONE;
 }
 
-Error VrHwc::acceptDisplayChanges(Display display) { return Error::NONE; }
+Error VrHwc::acceptDisplayChanges(Display /* display */) { return Error::NONE; }
 
 Error VrHwc::presentDisplay(Display display, int32_t* outPresentFence,
                             std::vector<Layer>* outLayers,
@@ -709,8 +713,8 @@
   return Error::NONE;
 }
 
-Error VrHwc::setLayerSidebandStream(Display display, Layer layer,
-                                    buffer_handle_t stream) {
+Error VrHwc::setLayerSidebandStream(Display display, Layer /* layer */,
+                                    buffer_handle_t /* stream */) {
   std::lock_guard<std::mutex> guard(mutex_);
   if (!FindDisplay(display))
     return Error::BAD_DISPLAY;