diff --git a/Changes.md b/Changes.md
index 1fadcef..be2a271 100644
--- a/Changes.md
+++ b/Changes.md
@@ -1,5 +1,9 @@
 # Build System Changes for Android.mk Writers
 
+## Deprecation of `BUILD_*` module types
+
+See [build/make/Deprecation.md](Deprecation.md) for the current status.
+
 ## `PRODUCT_HOST_PACKAGES` split from `PRODUCT_PACKAGES` {#PRODUCT_HOST_PACKAGES}
 
 Previously, adding a module to `PRODUCT_PACKAGES` that supported both the host
diff --git a/Deprecation.md b/Deprecation.md
new file mode 100644
index 0000000..6468f46
--- /dev/null
+++ b/Deprecation.md
@@ -0,0 +1,56 @@
+# Deprecation of Make
+
+We've made significant progress converting AOSP from Make to Soong (Android.mk
+to Android.bp), and we're ready to start turning off pieces of Make. If you
+have any problems converting, please contact us via:
+
+* The [android-building@googlegroups.com] group.
+* Our [public bug tracker](https://issuetracker.google.com/issues/new?component=381517).
+* Or privately through your existing contacts at Google.
+
+## Status
+
+[build/make/core/deprecation.mk] is the source of truth, but for easy browsing:
+
+| Module type                | State     |
+| -------------------------- | --------- |
+| `BUILD_HOST_TEST_CONFIG`   | Warning   |
+| `BUILD_TARGET_TEST_CONFIG` | Warning   |
+| `BUILD_*`                  | Available |
+
+## Module Type Deprecation Process
+
+We'll be turning off `BUILD_*` module types as all of the users are removed
+from AOSP (and Google's internal trees). The process will go something like
+this, using `BUILD_PACKAGE` as an example:
+
+* Prerequisite: all common users of `BUILD_PACKAGE` have been removed (some
+  device-specific ones may remain).
+* `BUILD_PACKAGE` will be moved from `AVAILABLE_BUILD_MODULE_TYPES` to
+  `DEFAULT_WARNING_BUILD_MODULE_TYPES` in [build/make/core/deprecation.mk]. This
+  will make referring to `BUILD_PACKAGE` a warning.
+* Any devices that still have warnings will have
+  `BUILD_BROKEN_USES_BUILD_PACKAGE := true` added to their `BoardConfig.mk`.
+* `BUILD_PACKAGE` will be switched from `DEFAULT_WARNING_BUILD_MODULE_TYPES` to
+  `DEFAULT_ERROR_BUILD_MODULE_TYPES`, which will turn referring to
+  `BUILD_PACKAGE` into an error unless the device has overridden it.
+* At some later point, after all devices in AOSP no longer set
+  `BUILD_BROKEN_USES_BUILD_PACKAGE`, `BUILD_PACKAGE` will be moved from
+  `DEFAULT_ERROR_BUILD_MODULE_TYPES` to `OBSOLETE_BUILD_MODULE_TYPES` and the
+  code will be removed. It will no longer be possible to use `BUILD_PACKAGE`.
+
+In most cases, we expect module types to stay in the default warning state for
+about two weeks before becoming an error by default. Then it will spend some
+amount of time in the default error state before moving to obsolete -- we'll
+try and keep that around for a while, but other development may cause those to
+break, and the fix may to be to obsolete them. There is no expectation that the
+`BUILD_BROKEN_USES_BUILD_*` workarounds will work in a future release, it's a
+short-term workaround.
+
+Just to be clear, the above process will happen on the AOSP master branch. So
+if you're following Android releases, none of the deprecation steps will be in
+Android Q, and the 2020 release will have jumped directly to the end for many
+module types.
+
+[android-building@googlegroups.com]: https://groups.google.com/forum/#!forum/android-building
+[build/make/core/deprecation.mk]: /core/deprecation.mk
diff --git a/core/board_config.mk b/core/board_config.mk
index d32e301..e4b88cb 100644
--- a/core/board_config.mk
+++ b/core/board_config.mk
@@ -92,6 +92,12 @@
   BUILD_BROKEN_ENG_DEBUG_TAGS \
   BUILD_BROKEN_USES_NETWORK \
 
+_build_broken_var_list += \
+  $(foreach m,$(AVAILABLE_BUILD_MODULE_TYPES) \
+              $(DEFAULT_WARNING_BUILD_MODULE_TYPES) \
+              $(DEFAULT_ERROR_BUILD_MODULE_TYPES), \
+    BUILD_BROKEN_USES_$(m))
+
 _board_true_false_vars := $(_build_broken_var_list)
 _board_strip_readonly_list += $(_build_broken_var_list)
 
@@ -511,3 +517,16 @@
   $(error System SDK versions '$(_unsupported_systemsdk_versions)' in BOARD_SYSTEMSDK_VERSIONS are not supported.\
           Supported versions are $(PLATFORM_SYSTEMSDK_VERSIONS))
 endif
+
+###########################################
+# Handle BUILD_BROKEN_USES_BUILD_*
+
+$(foreach m,$(DEFAULT_WARNING_BUILD_MODULE_TYPES),\
+  $(if $(filter false,$(BUILD_BROKEN_USES_$(m))),\
+    $(KATI_obsolete_var $(m),Please convert to Soong),\
+    $(KATI_deprecated_var $(m),Please convert to Soong)))
+
+$(foreach m,$(DEFAULT_ERROR_BUILD_MODULE_TYPES),\
+  $(if $(filter true,$(BUILD_BROKEN_USES_$(m))),\
+    $(KATI_deprecated_var $(m),Please convert to Soong),\
+    $(KATI_obsolete_var $(m),Please convert to Soong)))
diff --git a/core/config.mk b/core/config.mk
index b5fe866..16cd376 100644
--- a/core/config.mk
+++ b/core/config.mk
@@ -135,45 +135,48 @@
 # Build system internal files
 # ###############################################################
 
-BUILD_COMBOS:= $(BUILD_SYSTEM)/combo
+BUILD_COMBOS :=$= $(BUILD_SYSTEM)/combo
 
-CLEAR_VARS:= $(BUILD_SYSTEM)/clear_vars.mk
-BUILD_HOST_STATIC_LIBRARY:= $(BUILD_SYSTEM)/host_static_library.mk
-BUILD_HOST_SHARED_LIBRARY:= $(BUILD_SYSTEM)/host_shared_library.mk
-BUILD_STATIC_LIBRARY:= $(BUILD_SYSTEM)/static_library.mk
-BUILD_HEADER_LIBRARY:= $(BUILD_SYSTEM)/header_library.mk
-BUILD_AUX_STATIC_LIBRARY:= $(BUILD_SYSTEM)/aux_static_library.mk
-BUILD_AUX_EXECUTABLE:= $(BUILD_SYSTEM)/aux_executable.mk
-BUILD_SHARED_LIBRARY:= $(BUILD_SYSTEM)/shared_library.mk
-BUILD_EXECUTABLE:= $(BUILD_SYSTEM)/executable.mk
-BUILD_HOST_EXECUTABLE:= $(BUILD_SYSTEM)/host_executable.mk
-BUILD_PACKAGE:= $(BUILD_SYSTEM)/package.mk
-BUILD_PHONY_PACKAGE:= $(BUILD_SYSTEM)/phony_package.mk
-BUILD_RRO_PACKAGE:= $(BUILD_SYSTEM)/build_rro_package.mk
-BUILD_HOST_PREBUILT:= $(BUILD_SYSTEM)/host_prebuilt.mk
-BUILD_PREBUILT:= $(BUILD_SYSTEM)/prebuilt.mk
-BUILD_MULTI_PREBUILT:= $(BUILD_SYSTEM)/multi_prebuilt.mk
-BUILD_JAVA_LIBRARY:= $(BUILD_SYSTEM)/java_library.mk
-BUILD_STATIC_JAVA_LIBRARY:= $(BUILD_SYSTEM)/static_java_library.mk
-BUILD_HOST_JAVA_LIBRARY:= $(BUILD_SYSTEM)/host_java_library.mk
-BUILD_COPY_HEADERS := $(BUILD_SYSTEM)/copy_headers.mk
-BUILD_NATIVE_TEST := $(BUILD_SYSTEM)/native_test.mk
-BUILD_NATIVE_BENCHMARK := $(BUILD_SYSTEM)/native_benchmark.mk
-BUILD_HOST_NATIVE_TEST := $(BUILD_SYSTEM)/host_native_test.mk
-BUILD_FUZZ_TEST := $(BUILD_SYSTEM)/fuzz_test.mk
-BUILD_HOST_FUZZ_TEST := $(BUILD_SYSTEM)/host_fuzz_test.mk
+CLEAR_VARS :=$= $(BUILD_SYSTEM)/clear_vars.mk
 
-BUILD_SHARED_TEST_LIBRARY := $(BUILD_SYSTEM)/shared_test_lib.mk
-BUILD_HOST_SHARED_TEST_LIBRARY := $(BUILD_SYSTEM)/host_shared_test_lib.mk
-BUILD_STATIC_TEST_LIBRARY := $(BUILD_SYSTEM)/static_test_lib.mk
-BUILD_HOST_STATIC_TEST_LIBRARY := $(BUILD_SYSTEM)/host_static_test_lib.mk
+BUILD_HOST_STATIC_LIBRARY :=$= $(BUILD_SYSTEM)/host_static_library.mk
+BUILD_HOST_SHARED_LIBRARY :=$= $(BUILD_SYSTEM)/host_shared_library.mk
+BUILD_STATIC_LIBRARY :=$= $(BUILD_SYSTEM)/static_library.mk
+BUILD_HEADER_LIBRARY :=$= $(BUILD_SYSTEM)/header_library.mk
+BUILD_AUX_STATIC_LIBRARY :=$= $(BUILD_SYSTEM)/aux_static_library.mk
+BUILD_AUX_EXECUTABLE :=$= $(BUILD_SYSTEM)/aux_executable.mk
+BUILD_SHARED_LIBRARY :=$= $(BUILD_SYSTEM)/shared_library.mk
+BUILD_EXECUTABLE :=$= $(BUILD_SYSTEM)/executable.mk
+BUILD_HOST_EXECUTABLE :=$= $(BUILD_SYSTEM)/host_executable.mk
+BUILD_PACKAGE :=$= $(BUILD_SYSTEM)/package.mk
+BUILD_PHONY_PACKAGE :=$= $(BUILD_SYSTEM)/phony_package.mk
+BUILD_RRO_PACKAGE :=$= $(BUILD_SYSTEM)/build_rro_package.mk
+BUILD_HOST_PREBUILT :=$= $(BUILD_SYSTEM)/host_prebuilt.mk
+BUILD_PREBUILT :=$= $(BUILD_SYSTEM)/prebuilt.mk
+BUILD_MULTI_PREBUILT :=$= $(BUILD_SYSTEM)/multi_prebuilt.mk
+BUILD_JAVA_LIBRARY :=$= $(BUILD_SYSTEM)/java_library.mk
+BUILD_STATIC_JAVA_LIBRARY :=$= $(BUILD_SYSTEM)/static_java_library.mk
+BUILD_HOST_JAVA_LIBRARY :=$= $(BUILD_SYSTEM)/host_java_library.mk
+BUILD_COPY_HEADERS :=$= $(BUILD_SYSTEM)/copy_headers.mk
+BUILD_NATIVE_TEST :=$= $(BUILD_SYSTEM)/native_test.mk
+BUILD_NATIVE_BENCHMARK :=$= $(BUILD_SYSTEM)/native_benchmark.mk
+BUILD_HOST_NATIVE_TEST :=$= $(BUILD_SYSTEM)/host_native_test.mk
+BUILD_FUZZ_TEST :=$= $(BUILD_SYSTEM)/fuzz_test.mk
+BUILD_HOST_FUZZ_TEST :=$= $(BUILD_SYSTEM)/host_fuzz_test.mk
 
-BUILD_NOTICE_FILE := $(BUILD_SYSTEM)/notice_files.mk
-BUILD_HOST_DALVIK_JAVA_LIBRARY := $(BUILD_SYSTEM)/host_dalvik_java_library.mk
-BUILD_HOST_DALVIK_STATIC_JAVA_LIBRARY := $(BUILD_SYSTEM)/host_dalvik_static_java_library.mk
+BUILD_SHARED_TEST_LIBRARY :=$= $(BUILD_SYSTEM)/shared_test_lib.mk
+BUILD_HOST_SHARED_TEST_LIBRARY :=$= $(BUILD_SYSTEM)/host_shared_test_lib.mk
+BUILD_STATIC_TEST_LIBRARY :=$= $(BUILD_SYSTEM)/static_test_lib.mk
+BUILD_HOST_STATIC_TEST_LIBRARY :=$= $(BUILD_SYSTEM)/host_static_test_lib.mk
 
-BUILD_HOST_TEST_CONFIG := $(BUILD_SYSTEM)/host_test_config.mk
-BUILD_TARGET_TEST_CONFIG := $(BUILD_SYSTEM)/target_test_config.mk
+BUILD_NOTICE_FILE :=$= $(BUILD_SYSTEM)/notice_files.mk
+BUILD_HOST_DALVIK_JAVA_LIBRARY :=$= $(BUILD_SYSTEM)/host_dalvik_java_library.mk
+BUILD_HOST_DALVIK_STATIC_JAVA_LIBRARY :=$= $(BUILD_SYSTEM)/host_dalvik_static_java_library.mk
+
+BUILD_HOST_TEST_CONFIG :=$= $(BUILD_SYSTEM)/host_test_config.mk
+BUILD_TARGET_TEST_CONFIG :=$= $(BUILD_SYSTEM)/target_test_config.mk
+
+include $(BUILD_SYSTEM)/deprecation.mk
 
 # ###############################################################
 # Parse out any modifier targets.
diff --git a/core/deprecation.mk b/core/deprecation.mk
new file mode 100644
index 0000000..cbc938a
--- /dev/null
+++ b/core/deprecation.mk
@@ -0,0 +1,55 @@
+# These module types can still be used without warnings or errors.
+AVAILABLE_BUILD_MODULE_TYPES :=$= \
+  BUILD_AUX_EXECUTABLE \
+  BUILD_AUX_STATIC_LIBRARY \
+  BUILD_COPY_HEADERS \
+  BUILD_EXECUTABLE \
+  BUILD_FUZZ_TEST \
+  BUILD_HEADER_LIBRARY \
+  BUILD_HOST_DALVIK_JAVA_LIBRARY \
+  BUILD_HOST_DALVIK_STATIC_JAVA_LIBRARY \
+  BUILD_HOST_EXECUTABLE \
+  BUILD_HOST_FUZZ_TEST \
+  BUILD_HOST_JAVA_LIBRARY \
+  BUILD_HOST_NATIVE_TEST \
+  BUILD_HOST_PREBUILT \
+  BUILD_HOST_SHARED_LIBRARY \
+  BUILD_HOST_SHARED_TEST_LIBRARY \
+  BUILD_HOST_STATIC_LIBRARY \
+  BUILD_HOST_STATIC_TEST_LIBRARY \
+  BUILD_JAVA_LIBRARY \
+  BUILD_MULTI_PREBUILT \
+  BUILD_NATIVE_BENCHMARK \
+  BUILD_NATIVE_TEST \
+  BUILD_NOTICE_FILE \
+  BUILD_PACKAGE \
+  BUILD_PHONY_PACKAGE \
+  BUILD_PREBUILT \
+  BUILD_RRO_PACKAGE \
+  BUILD_SHARED_LIBRARY \
+  BUILD_SHARED_TEST_LIBRARY \
+  BUILD_STATIC_JAVA_LIBRARY \
+  BUILD_STATIC_LIBRARY \
+  BUILD_STATIC_TEST_LIBRARY \
+
+# These are BUILD_* variables that will throw a warning when used. This is
+# generally a temporary state until all the devices are marked with the
+# relevant BUILD_BROKEN_USES_BUILD_* variables, then these would move to
+# DEFAULT_ERROR_BUILD_MODULE_TYPES.
+DEFAULT_WARNING_BUILD_MODULE_TYPES :=$= \
+  BUILD_HOST_TEST_CONFIG \
+  BUILD_TARGET_TEST_CONFIG \
+
+# These are BUILD_* variables that are errors to reference, but you can set
+# BUILD_BROKEN_USES_BUILD_* in your BoardConfig.mk in order to turn them back
+# to warnings.
+DEFAULT_ERROR_BUILD_MODULE_TYPES :=$= \
+
+# These are BUILD_* variables that are always errors to reference.
+# Setting the BUILD_BROKEN_USES_BUILD_* variables is also an error.
+OBSOLETE_BUILD_MODULE_TYPES :=$= \
+
+$(foreach m,$(OBSOLETE_BUILD_MODULE_TYPES),\
+  $(KATI_obsolete_var $(m),Please convert to Soong) \
+  $(KATI_obsolete_var BUILD_BROKEN_USES_$(m),Please convert to Soong))
+
diff --git a/core/soong_config.mk b/core/soong_config.mk
index c01fc98..46e026a 100644
--- a/core/soong_config.mk
+++ b/core/soong_config.mk
@@ -165,7 +165,7 @@
 $(call add_json_list, ProductHiddenAPIStubsSystem,       $(PRODUCT_HIDDENAPI_STUBS_SYSTEM))
 $(call add_json_list, ProductHiddenAPIStubsTest,         $(PRODUCT_HIDDENAPI_STUBS_TEST))
 
-$(call add_json_str,  TargetFSConfigGen,                 $(TARGET_FS_CONFIG_GEN))
+$(call add_json_list, TargetFSConfigGen,                 $(TARGET_FS_CONFIG_GEN))
 
 $(call add_json_map, VendorVars)
 $(foreach namespace,$(SOONG_CONFIG_NAMESPACES),\
diff --git a/target/product/mainline_system.mk b/target/product/mainline_system.mk
index d75809c..66207df 100644
--- a/target/product/mainline_system.mk
+++ b/target/product/mainline_system.mk
@@ -18,6 +18,8 @@
 $(call inherit-product, $(SRC_TARGET_DIR)/product/handheld_system.mk)
 $(call inherit-product, $(SRC_TARGET_DIR)/product/telephony_system.mk)
 $(call inherit-product, $(SRC_TARGET_DIR)/product/languages_default.mk)
+# Enable updating of APEXes
+$(call inherit-product, $(SRC_TARGET_DIR)/product/updatable_apex.mk)
 # Add adb keys to debuggable AOSP builds (if they exist)
 $(call inherit-product-if-exists, vendor/google/security/adb/vendor_key.mk)
 
diff --git a/target/product/updatable_apex.mk b/target/product/updatable_apex.mk
new file mode 100644
index 0000000..4b31578
--- /dev/null
+++ b/target/product/updatable_apex.mk
@@ -0,0 +1,20 @@
+#
+# Copyright (C) 2019 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.
+#
+
+# Inherit this when the target needs to support updating APEXes
+
+PRODUCT_PROPERTY_OVERRIDES := ro.apex.updatable=true
+PRODUCT_PACKAGES := com.android.apex.cts.shim.v1_prebuilt
diff --git a/tools/fs_config/Android.bp b/tools/fs_config/Android.bp
index d6fae2d..d9a48d7 100644
--- a/tools/fs_config/Android.bp
+++ b/tools/fs_config/Android.bp
@@ -42,7 +42,7 @@
 genrule {
     name: "oemaids_header_gen",
     tool_files: ["fs_config_generator.py"],
-    cmd: "$(location fs_config_generator.py) oemaid --aid-header=$(location :android_filesystem_config_header) $(location :target_fs_config_gen) >$(out)",
+    cmd: "$(location fs_config_generator.py) oemaid --aid-header=$(location :android_filesystem_config_header) $(locations :target_fs_config_gen) >$(out)",
     srcs: [
         ":target_fs_config_gen",
         ":android_filesystem_config_header",
@@ -62,7 +62,7 @@
 genrule {
     name: "passwd_gen",
     tool_files: ["fs_config_generator.py"],
-    cmd: "$(location fs_config_generator.py) passwd --required-prefix=vendor_ --aid-header=$(location :android_filesystem_config_header) $(location :target_fs_config_gen) >$(out)",
+    cmd: "$(location fs_config_generator.py) passwd --required-prefix=vendor_ --aid-header=$(location :android_filesystem_config_header) $(locations :target_fs_config_gen) >$(out)",
     srcs: [
         ":target_fs_config_gen",
         ":android_filesystem_config_header",
@@ -82,7 +82,7 @@
 genrule {
     name: "group_gen",
     tool_files: ["fs_config_generator.py"],
-    cmd: "$(location fs_config_generator.py) group --required-prefix=vendor_ --aid-header=$(location :android_filesystem_config_header) $(location :target_fs_config_gen) >$(out)",
+    cmd: "$(location fs_config_generator.py) group --required-prefix=vendor_ --aid-header=$(location :android_filesystem_config_header) $(locations :target_fs_config_gen) >$(out)",
     srcs: [
         ":target_fs_config_gen",
         ":android_filesystem_config_header",
diff --git a/tools/fs_config/fs_config.go b/tools/fs_config/fs_config.go
index 869cb3d..16bcefa 100644
--- a/tools/fs_config/fs_config.go
+++ b/tools/fs_config/fs_config.go
@@ -24,7 +24,7 @@
 	android.RegisterModuleType("target_fs_config_gen_filegroup", targetFSConfigGenFactory)
 }
 
-// target_fs_config_gen_filegroup is used to expose the file pointed to by TARGET_FS_CONFIG_GEN to
+// target_fs_config_gen_filegroup is used to expose the files pointed to by TARGET_FS_CONFIG_GEN to
 // genrules in Soong. If TARGET_FS_CONFIG_GEN is empty, it will export an empty file instead.
 func targetFSConfigGenFactory() android.Module {
 	module := &targetFSConfigGen{}
@@ -36,17 +36,17 @@
 
 type targetFSConfigGen struct {
 	android.ModuleBase
-	path android.Path
+	paths android.Paths
 }
 
 func (targetFSConfigGen) DepsMutator(ctx android.BottomUpMutatorContext) {}
 
 func (t *targetFSConfigGen) GenerateAndroidBuildActions(ctx android.ModuleContext) {
-	if ret := ctx.DeviceConfig().TargetFSConfigGen(); ret != nil && *ret != "" {
-		t.path = android.PathForSource(ctx, *ret)
+	if ret := ctx.DeviceConfig().TargetFSConfigGen(); len(ret) != 0 {
+		t.paths = android.PathsForSource(ctx, ret)
 	} else {
 		path := android.PathForModuleGen(ctx, "empty")
-		t.path = path
+		t.paths = android.Paths{path}
 
 		rule := android.NewRuleBuilder()
 		rule.Command().Text("rm -rf").Output(path)
@@ -56,5 +56,5 @@
 }
 
 func (t *targetFSConfigGen) Srcs() android.Paths {
-	return android.Paths{t.path}
+	return t.paths
 }
diff --git a/tools/releasetools/merge_target_files.py b/tools/releasetools/merge_target_files.py
index 77c774a..e306807 100755
--- a/tools/releasetools/merge_target_files.py
+++ b/tools/releasetools/merge_target_files.py
@@ -13,11 +13,11 @@
 # WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. See the
 # License for the specific language governing permissions and limitations under
 # the License.
+"""This script merges two partial target files packages.
 
-"""
-This script merges two partial target files packages (one of which contains
-system files, and the other contains non-system files) together, producing a
-complete target files package that can be used to generate an OTA package.
+One package contains system files, and the other contains non-system files.
+It produces a complete target files package that can be used to generate an
+OTA package.
 
 Usage: merge_target_files.py [args]
 
@@ -126,8 +126,8 @@
     'META/*',
 ]
 
-# default_system_misc_info_keys is a list of keys to obtain from the system instance of
-# META/misc_info.txt. The remaining keys from the other instance.
+# default_system_misc_info_keys is a list of keys to obtain from the system
+# instance of META/misc_info.txt. The remaining keys from the other instance.
 
 default_system_misc_info_keys = [
     'avb_system_hashtree_enable',
@@ -185,10 +185,8 @@
 
   Args:
     target_files: The target files zip archive from which to extract items.
-
     target_files_temp_dir: The temporary directory where the extracted items
-    will land.
-
+      will land.
     extract_item_list: A list of items to extract.
   """
 
@@ -198,9 +196,7 @@
   # zip file. Otherwise, the extraction step will fail.
 
   with zipfile.ZipFile(
-      target_files,
-      'r',
-      allowZip64=True) as target_files_zipfile:
+      target_files, 'r', allowZip64=True) as target_files_zipfile:
     target_files_namelist = target_files_zipfile.namelist()
 
   filtered_extract_item_list = []
@@ -214,18 +210,17 @@
   # Extract from target_files into target_files_temp_dir the
   # filtered_extract_item_list.
 
-  common.UnzipToDir(
-      target_files,
-      target_files_temp_dir,
-      filtered_extract_item_list)
+  common.UnzipToDir(target_files, target_files_temp_dir,
+                    filtered_extract_item_list)
 
 
 def copy_items(from_dir, to_dir, patterns):
   """Similar to extract_items() except uses an input dir instead of zip."""
   file_paths = []
   for dirpath, _, filenames in os.walk(from_dir):
-    file_paths.extend(os.path.relpath(path=os.path.join(dirpath, filename),
-                                      start=from_dir) for filename in filenames)
+    file_paths.extend(
+        os.path.relpath(path=os.path.join(dirpath, filename), start=from_dir)
+        for filename in filenames)
 
   filtered_file_paths = set()
   for pattern in patterns:
@@ -250,26 +245,25 @@
 
   Args:
     config_file_path: The path to the config file to open and read.
+
+  Returns:
+    The list of strings in the config file.
   """
   with open(config_file_path) as config_file:
     return config_file.read().splitlines()
 
 
-def validate_config_lists(
-    system_item_list,
-    system_misc_info_keys,
-    other_item_list):
+def validate_config_lists(system_item_list, system_misc_info_keys,
+                          other_item_list):
   """Performs validations on the merge config lists.
 
   Args:
-    system_item_list: The list of items to extract from the partial
-    system target files package as is.
-
-    system_misc_info_keys: A list of keys to obtain from the system instance
-    of META/misc_info.txt. The remaining keys from the other instance.
-
-    other_item_list: The list of items to extract from the partial
-    other target files package as is.
+    system_item_list: The list of items to extract from the partial system
+      target files package as is.
+    system_misc_info_keys: A list of keys to obtain from the system instance of
+      META/misc_info.txt. The remaining keys from the other instance.
+    other_item_list: The list of items to extract from the partial other target
+      files package as is.
 
   Returns:
     False if a validation fails, otherwise true.
@@ -284,7 +278,7 @@
   # by the default config lists.
   difference = default_combined_item_set.difference(combined_item_set)
   if difference:
-    logger.error('Missing merge config items: %s' % list(difference))
+    logger.error('Missing merge config items: %s', list(difference))
     logger.error('Please ensure missing items are in either the '
                  'system-item-list or other-item-list files provided to '
                  'this script.')
@@ -299,11 +293,10 @@
   return True
 
 
-def process_ab_partitions_txt(
-    system_target_files_temp_dir,
-    other_target_files_temp_dir,
-    output_target_files_temp_dir):
-  """Perform special processing for META/ab_partitions.txt
+def process_ab_partitions_txt(system_target_files_temp_dir,
+                              other_target_files_temp_dir,
+                              output_target_files_temp_dir):
+  """Perform special processing for META/ab_partitions.txt.
 
   This function merges the contents of the META/ab_partitions.txt files from
   the system directory and the other directory, placing the merged result in
@@ -314,22 +307,20 @@
   names.
 
   Args:
-    system_target_files_temp_dir: The name of a directory containing the
-    special items extracted from the system target files package.
-
-    other_target_files_temp_dir: The name of a directory containing the
-    special items extracted from the other target files package.
-
-    output_target_files_temp_dir: The name of a directory that will be used
-    to create the output target files package after all the special cases
-    are processed.
+    system_target_files_temp_dir: The name of a directory containing the special
+      items extracted from the system target files package.
+    other_target_files_temp_dir: The name of a directory containing the special
+      items extracted from the other target files package.
+    output_target_files_temp_dir: The name of a directory that will be used to
+      create the output target files package after all the special cases are
+      processed.
   """
 
-  system_ab_partitions_txt = os.path.join(
-      system_target_files_temp_dir, 'META', 'ab_partitions.txt')
+  system_ab_partitions_txt = os.path.join(system_target_files_temp_dir, 'META',
+                                          'ab_partitions.txt')
 
-  other_ab_partitions_txt = os.path.join(
-      other_target_files_temp_dir, 'META', 'ab_partitions.txt')
+  other_ab_partitions_txt = os.path.join(other_target_files_temp_dir, 'META',
+                                         'ab_partitions.txt')
 
   with open(system_ab_partitions_txt) as f:
     system_ab_partitions = f.read().splitlines()
@@ -339,8 +330,8 @@
 
   output_ab_partitions = set(system_ab_partitions + other_ab_partitions)
 
-  output_ab_partitions_txt = os.path.join(
-      output_target_files_temp_dir, 'META', 'ab_partitions.txt')
+  output_ab_partitions_txt = os.path.join(output_target_files_temp_dir, 'META',
+                                          'ab_partitions.txt')
 
   with open(output_ab_partitions_txt, 'w') as output:
     for partition in sorted(output_ab_partitions):
@@ -348,42 +339,35 @@
 
 
 def append_recovery_to_filesystem_config(output_target_files_temp_dir):
-  """Perform special processing for META/filesystem_config.txt
+  """Perform special processing for META/filesystem_config.txt.
 
   This function appends recovery information to META/filesystem_config.txt
   so that recovery patch regeneration will succeed.
 
   Args:
-    output_target_files_temp_dir: The name of a directory that will be used
-    to create the output target files package after all the special cases
-    are processed. We find filesystem_config.txt here.
+    output_target_files_temp_dir: The name of a directory that will be used to
+      create the output target files package after all the special cases are
+      processed. We find filesystem_config.txt here.
   """
 
-  filesystem_config_txt = os.path.join(
-      output_target_files_temp_dir,
-      'META',
-      'filesystem_config.txt')
+  filesystem_config_txt = os.path.join(output_target_files_temp_dir, 'META',
+                                       'filesystem_config.txt')
 
   with open(filesystem_config_txt, 'a') as f:
     # TODO(bpeckham) this data is hard coded. It should be generated
     # programmatically.
-    f.write(
-        'system/bin/install-recovery.sh 0 0 750 '
-        'selabel=u:object_r:install_recovery_exec:s0 capabilities=0x0\n')
-    f.write(
-        'system/recovery-from-boot.p 0 0 644 '
-        'selabel=u:object_r:system_file:s0 capabilities=0x0\n')
-    f.write(
-        'system/etc/recovery.img 0 0 440 '
-        'selabel=u:object_r:install_recovery_exec:s0 capabilities=0x0\n')
+    f.write('system/bin/install-recovery.sh 0 0 750 '
+            'selabel=u:object_r:install_recovery_exec:s0 capabilities=0x0\n')
+    f.write('system/recovery-from-boot.p 0 0 644 '
+            'selabel=u:object_r:system_file:s0 capabilities=0x0\n')
+    f.write('system/etc/recovery.img 0 0 440 '
+            'selabel=u:object_r:install_recovery_exec:s0 capabilities=0x0\n')
 
 
-def process_misc_info_txt(
-    system_target_files_temp_dir,
-    other_target_files_temp_dir,
-    output_target_files_temp_dir,
-    system_misc_info_keys):
-  """Perform special processing for META/misc_info.txt
+def process_misc_info_txt(system_target_files_temp_dir,
+                          other_target_files_temp_dir,
+                          output_target_files_temp_dir, system_misc_info_keys):
+  """Perform special processing for META/misc_info.txt.
 
   This function merges the contents of the META/misc_info.txt files from the
   system directory and the other directory, placing the merged result in the
@@ -392,18 +376,15 @@
   content.
 
   Args:
-    system_target_files_temp_dir: The name of a directory containing the
-    special items extracted from the system target files package.
-
-    other_target_files_temp_dir: The name of a directory containing the
-    special items extracted from the other target files package.
-
-    output_target_files_temp_dir: The name of a directory that will be used
-    to create the output target files package after all the special cases
-    are processed.
-
-    system_misc_info_keys: A list of keys to obtain from the system instance
-    of META/misc_info.txt. The remaining keys from the other instance.
+    system_target_files_temp_dir: The name of a directory containing the special
+      items extracted from the system target files package.
+    other_target_files_temp_dir: The name of a directory containing the special
+      items extracted from the other target files package.
+    output_target_files_temp_dir: The name of a directory that will be used to
+      create the output target files package after all the special cases are
+      processed.
+    system_misc_info_keys: A list of keys to obtain from the system instance of
+      META/misc_info.txt. The remaining keys from the other instance.
   """
 
   def read_helper(d):
@@ -434,19 +415,18 @@
     # Partition groups and group sizes are defined by the other (non-system)
     # misc info file because these values may vary for each board that uses
     # a shared system image.
-    for partition_group in merged_info_dict['super_partition_groups'].split(' '):
+    for partition_group in merged_info_dict['super_partition_groups'].split(
+        ' '):
       if ('super_%s_group_size' % partition_group) not in merged_info_dict:
         raise ValueError(
             'Other META/misc_info.txt does not contain required key '
             'super_%s_group_size.' % partition_group)
       key = 'super_%s_partition_list' % partition_group
-      merged_info_dict[key] = '%s %s' % (
-        system_info_dict.get(key, ''),
-        merged_info_dict.get(key, ''))
+      merged_info_dict[key] = '%s %s' % (system_info_dict.get(
+          key, ''), merged_info_dict.get(key, ''))
 
-  output_misc_info_txt = os.path.join(
-      output_target_files_temp_dir,
-      'META', 'misc_info.txt')
+  output_misc_info_txt = os.path.join(output_target_files_temp_dir, 'META',
+                                      'misc_info.txt')
 
   sorted_keys = sorted(merged_info_dict.keys())
 
@@ -464,12 +444,11 @@
 
   Args:
     temp_dir: The name of a scratch directory that this function can use for
-    intermediate files generated during processing.
-
+      intermediate files generated during processing.
     output_target_files_temp_dir: The name of the working directory that must
-    already contain plat_file_contexts and vendor_file_contexts (in the
-    appropriate sub directories), and to which META/file_contexts.bin will be
-    written.
+      already contain plat_file_contexts and vendor_file_contexts (in the
+      appropriate sub directories), and to which META/file_contexts.bin will be
+      written.
   """
 
   # To create a merged file_contexts.bin file, we use the system and vendor
@@ -490,9 +469,8 @@
   for partition in ['SYSTEM', 'VENDOR', 'PRODUCT', 'ODM']:
     prefix = 'plat' if partition == 'SYSTEM' else partition.lower()
 
-    file_contexts = os.path.join(
-        output_target_files_temp_dir,
-        partition, 'etc', 'selinux', prefix + '_file_contexts')
+    file_contexts = os.path.join(output_target_files_temp_dir, partition, 'etc',
+                                 'selinux', prefix + '_file_contexts')
 
     mandatory = partition in ['SYSTEM', 'VENDOR']
 
@@ -518,27 +496,23 @@
 
   # Finally, the compile step creates the final META/file_contexts.bin.
 
-  file_contexts_bin = os.path.join(
-      output_target_files_temp_dir,
-      'META', 'file_contexts.bin')
+  file_contexts_bin = os.path.join(output_target_files_temp_dir, 'META',
+                                   'file_contexts.bin')
 
   command = [
       'sefcontext_compile',
-      '-o', file_contexts_bin,
+      '-o',
+      file_contexts_bin,
       sorted_file_contexts_txt,
   ]
 
   common.RunAndWait(command, verbose=True)
 
 
-def process_special_cases(
-    temp_dir,
-    system_target_files_temp_dir,
-    other_target_files_temp_dir,
-    output_target_files_temp_dir,
-    system_misc_info_keys,
-    rebuild_recovery
-):
+def process_special_cases(temp_dir, system_target_files_temp_dir,
+                          other_target_files_temp_dir,
+                          output_target_files_temp_dir, system_misc_info_keys,
+                          rebuild_recovery):
   """Perform special-case processing for certain target files items.
 
   Certain files in the output target files package require special-case
@@ -546,23 +520,18 @@
 
   Args:
     temp_dir: The name of a scratch directory that this function can use for
-    intermediate files generated during processing.
-
-    system_target_files_temp_dir: The name of a directory containing the
-    special items extracted from the system target files package.
-
-    other_target_files_temp_dir: The name of a directory containing the
-    special items extracted from the other target files package.
-
-    output_target_files_temp_dir: The name of a directory that will be used
-    to create the output target files package after all the special cases
-    are processed.
-
-    system_misc_info_keys: A list of keys to obtain from the system instance
-    of META/misc_info.txt. The remaining keys from the other instance.
-
+      intermediate files generated during processing.
+    system_target_files_temp_dir: The name of a directory containing the special
+      items extracted from the system target files package.
+    other_target_files_temp_dir: The name of a directory containing the special
+      items extracted from the other target files package.
+    output_target_files_temp_dir: The name of a directory that will be used to
+      create the output target files package after all the special cases are
+      processed.
+    system_misc_info_keys: A list of keys to obtain from the system instance of
+      META/misc_info.txt. The remaining keys from the other instance.
     rebuild_recovery: If true, rebuild the recovery patch used by non-A/B
-    devices and write it to the system image.
+      devices and write it to the system image.
   """
 
   if 'ab_update' in system_misc_info_keys:
@@ -586,19 +555,11 @@
       output_target_files_temp_dir=output_target_files_temp_dir)
 
 
-def merge_target_files(
-    temp_dir,
-    system_target_files,
-    system_item_list,
-    system_misc_info_keys,
-    other_target_files,
-    other_item_list,
-    output_target_files,
-    output_dir,
-    output_item_list,
-    output_ota,
-    output_super_empty,
-    rebuild_recovery):
+def merge_target_files(temp_dir, system_target_files, system_item_list,
+                       system_misc_info_keys, other_target_files,
+                       other_item_list, output_target_files, output_dir,
+                       output_item_list, output_ota, output_super_empty,
+                       rebuild_recovery):
   """Merge two target files packages together.
 
   This function takes system and other target files packages as input, performs
@@ -607,45 +568,35 @@
 
   Args:
     temp_dir: The name of a directory we use when we extract items from the
-    input target files packages, and also a scratch directory that we use for
-    temporary files.
-
+      input target files packages, and also a scratch directory that we use for
+      temporary files.
     system_target_files: The name of the zip archive containing the system
-    partial target files package.
-
+      partial target files package.
     system_item_list: The list of items to extract from the partial system
-    target files package as is, meaning these items will land in the output
-    target files package exactly as they appear in the input partial system
-    target files package.
-
+      target files package as is, meaning these items will land in the output
+      target files package exactly as they appear in the input partial system
+      target files package.
     system_misc_info_keys: The list of keys to obtain from the system instance
-    of META/misc_info.txt. The remaining keys from the other instance.
-
-    other_target_files: The name of the zip archive containing the other
-    partial target files package.
-
-    other_item_list: The list of items to extract from the partial other
-    target files package as is, meaning these items will land in the output
-    target files package exactly as they appear in the input partial other
-    target files package.
-
-    output_target_files: The name of the output zip archive target files
-    package created by merging system and other.
-
+      of META/misc_info.txt. The remaining keys from the other instance.
+    other_target_files: The name of the zip archive containing the other partial
+      target files package.
+    other_item_list: The list of items to extract from the partial other target
+      files package as is, meaning these items will land in the output target
+      files package exactly as they appear in the input partial other target
+      files package.
+    output_target_files: The name of the output zip archive target files package
+      created by merging system and other.
+    output_dir: The destination directory for saving merged files.
+    output_item_list: The list of items to copy into the output_dir.
     output_ota: The name of the output zip archive ota package.
-
     output_super_empty: If provided, creates a super_empty.img file from the
-    merged target files package and saves it at this path.
-
+      merged target files package and saves it at this path.
     rebuild_recovery: If true, rebuild the recovery patch used by non-A/B
-    devices and write it to the system image.
+      devices and write it to the system image.
   """
 
-  logger.info(
-      'starting: merge system %s and other %s into output %s',
-      system_target_files,
-      other_target_files,
-      output_target_files)
+  logger.info('starting: merge system %s and other %s into output %s',
+              system_target_files, other_target_files, output_target_files)
 
   # Create directory names that we'll use when we extract files from system,
   # and other, and for zipping the final output.
@@ -706,8 +657,9 @@
   # Create super_empty.img using the merged misc_info.txt.
 
   if output_super_empty:
-    misc_info_txt = os.path.join(output_target_files_temp_dir,
-                                 'META', 'misc_info.txt')
+    misc_info_txt = os.path.join(output_target_files_temp_dir, 'META',
+                                 'misc_info.txt')
+
     def read_helper():
       with open(misc_info_txt) as f:
         return list(f.read().splitlines())
@@ -718,9 +670,9 @@
           'Building super_empty.img requires use_dynamic_partitions=true.')
 
     build_super_image_args = [
-      '--verbose',
-      misc_info_txt,
-      output_super_empty,
+        '--verbose',
+        misc_info_txt,
+        output_super_empty,
     ]
     build_super_image.main(build_super_image_args)
 
@@ -744,8 +696,8 @@
 
   output_zip = os.path.abspath(output_target_files)
   output_target_files_list = os.path.join(temp_dir, 'output.list')
-  output_target_files_meta_dir = os.path.join(
-      output_target_files_temp_dir, 'META')
+  output_target_files_meta_dir = os.path.join(output_target_files_temp_dir,
+                                              'META')
 
   command = [
       'find',
@@ -754,13 +706,8 @@
   # TODO(bpeckham): sort this to be more like build.
   meta_content = common.RunAndCheckOutput(command, verbose=False)
   command = [
-      'find',
-      output_target_files_temp_dir,
-      '-path',
-      output_target_files_meta_dir,
-      '-prune',
-      '-o',
-      '-print'
+      'find', output_target_files_temp_dir, '-path',
+      output_target_files_meta_dir, '-prune', '-o', '-print'
   ]
   # TODO(bpeckham): sort this to be more like build.
   other_content = common.RunAndCheckOutput(command, verbose=False)
@@ -772,9 +719,12 @@
   command = [
       'soong_zip',
       '-d',
-      '-o', output_zip,
-      '-C', output_target_files_temp_dir,
-      '-l', output_target_files_list,
+      '-o',
+      output_zip,
+      '-C',
+      output_target_files_temp_dir,
+      '-l',
+      output_target_files_list,
   ]
   logger.info('creating %s', output_target_files)
   common.RunAndWait(command, verbose=True)
@@ -796,9 +746,8 @@
   directory. It also cleans up the temporary directory.
 
   Args:
-    func: The function to call. Should accept one parameter, the path to
-    the temporary directory.
-
+    func: The function to call. Should accept one parameter, the path to the
+      temporary directory.
     keep_tmp: Keep the temporary directory after processing is complete.
   """
 
@@ -858,7 +807,8 @@
     return True
 
   args = common.ParseOptions(
-      sys.argv[1:], __doc__,
+      sys.argv[1:],
+      __doc__,
       extra_long_opts=[
           'system-target-files=',
           'system-item-list=',
@@ -875,13 +825,10 @@
       ],
       extra_option_handler=option_handler)
 
-  if (len(args) != 0 or
-      OPTIONS.system_target_files is None or
-      OPTIONS.other_target_files is None or (
-        OPTIONS.output_target_files is None and
-        OPTIONS.output_dir is None) or (
-        OPTIONS.output_dir is not None and
-        OPTIONS.output_item_list is None)):
+  if (args or OPTIONS.system_target_files is None or
+      OPTIONS.other_target_files is None or
+      (OPTIONS.output_target_files is None and OPTIONS.output_dir is None) or
+      (OPTIONS.output_dir is not None and OPTIONS.output_item_list is None)):
     common.Usage(__doc__)
     sys.exit(1)
 
@@ -924,8 +871,7 @@
           output_item_list=output_item_list,
           output_ota=OPTIONS.output_ota,
           output_super_empty=OPTIONS.output_super_empty,
-          rebuild_recovery=OPTIONS.rebuild_recovery),
-      OPTIONS.keep_tmp)
+          rebuild_recovery=OPTIONS.rebuild_recovery), OPTIONS.keep_tmp)
 
 
 if __name__ == '__main__':