diff --git a/services/surfaceflinger/tests/unittests/Android.bp b/services/surfaceflinger/tests/unittests/Android.bp
index 95c54b8..8f1f5e5 100644
--- a/services/surfaceflinger/tests/unittests/Android.bp
+++ b/services/surfaceflinger/tests/unittests/Android.bp
@@ -27,6 +27,7 @@
         "mock/DisplayHardware/MockPowerAdvisor.cpp",
         "mock/gui/MockGraphicBufferConsumer.cpp",
         "mock/gui/MockGraphicBufferProducer.cpp",
+        "mock/MockDispSync.cpp",
         "mock/MockEventControlThread.cpp",
         "mock/MockEventThread.cpp",
         "mock/MockMessageQueue.cpp",
diff --git a/services/surfaceflinger/tests/unittests/DisplayTransactionTest.cpp b/services/surfaceflinger/tests/unittests/DisplayTransactionTest.cpp
index 58d3879..508875d 100644
--- a/services/surfaceflinger/tests/unittests/DisplayTransactionTest.cpp
+++ b/services/surfaceflinger/tests/unittests/DisplayTransactionTest.cpp
@@ -25,6 +25,7 @@
 #include "TestableSurfaceFlinger.h"
 #include "mock/DisplayHardware/MockComposer.h"
 #include "mock/DisplayHardware/MockDisplaySurface.h"
+#include "mock/MockDispSync.h"
 #include "mock/MockEventControlThread.h"
 #include "mock/MockEventThread.h"
 #include "mock/MockMessageQueue.h"
@@ -119,6 +120,7 @@
     Hwc2::mock::Composer* mComposer = nullptr;
     mock::MessageQueue* mMessageQueue = new mock::MessageQueue();
     mock::SurfaceInterceptor* mSurfaceInterceptor = new mock::SurfaceInterceptor();
+    mock::DispSync* mPrimaryDispSync = new mock::DispSync();
 
     // These mocks are created only when expected to be created via a factory.
     sp<mock::GraphicBufferConsumer> mConsumer;
@@ -154,6 +156,7 @@
     mFlinger.mutableEventQueue().reset(mMessageQueue);
     mFlinger.setupRenderEngine(std::unique_ptr<RE::RenderEngine>(mRenderEngine));
     mFlinger.mutableInterceptor().reset(mSurfaceInterceptor);
+    mFlinger.mutablePrimaryDispSync().reset(mPrimaryDispSync);
 
     injectMockComposer(0);
 }
@@ -961,6 +964,9 @@
     // The call clears the current render engine surface
     EXPECT_CALL(*mRenderEngine, resetCurrentSurface());
 
+    // The call ends any display resyncs
+    EXPECT_CALL(*mPrimaryDispSync, endResync()).Times(1);
+
     // --------------------------------------------------------------------
     // Invocation
 
@@ -2400,6 +2406,24 @@
     }
 };
 
+struct DispSyncIsSupportedVariant {
+    static void setupBeginResyncCallExpectations(DisplayTransactionTest* test) {
+        EXPECT_CALL(*test->mPrimaryDispSync, reset()).Times(1);
+        EXPECT_CALL(*test->mPrimaryDispSync, setPeriod(DEFAULT_REFRESH_RATE)).Times(1);
+        EXPECT_CALL(*test->mPrimaryDispSync, beginResync()).Times(1);
+    }
+
+    static void setupEndResyncCallExpectations(DisplayTransactionTest* test) {
+        EXPECT_CALL(*test->mPrimaryDispSync, endResync()).Times(1);
+    }
+};
+
+struct DispSyncNotSupportedVariant {
+    static void setupBeginResyncCallExpectations(DisplayTransactionTest* /* test */) {}
+
+    static void setupEndResyncCallExpectations(DisplayTransactionTest* /* test */) {}
+};
+
 // --------------------------------------------------------------------
 // Note:
 //
@@ -2421,6 +2445,7 @@
     static void setupCallExpectations(DisplayTransactionTest* test) {
         Case::setupComposerCallExpectations(test, IComposerClient::PowerMode::ON);
         Case::EventThread::setupAcquireAndEnableVsyncCallExpectations(test);
+        Case::DispSync::setupBeginResyncCallExpectations(test);
         Case::setupRepaintEverythingCallExpectations(test);
     }
 
@@ -2450,6 +2475,7 @@
     template <typename Case>
     static void setupCallExpectations(DisplayTransactionTest* test) {
         Case::EventThread::setupReleaseAndDisableVsyncCallExpectations(test);
+        Case::DispSync::setupEndResyncCallExpectations(test);
         Case::setupComposerCallExpectations(test, IComposerClient::PowerMode::OFF);
     }
 
@@ -2485,6 +2511,7 @@
     template <typename Case>
     static void setupCallExpectations(DisplayTransactionTest* test) {
         Case::EventThread::setupAcquireAndEnableVsyncCallExpectations(test);
+        Case::DispSync::setupBeginResyncCallExpectations(test);
         Case::setupComposerCallExpectations(test, Case::Doze::ACTUAL_POWER_MODE_FOR_DOZE);
     }
 };
@@ -2503,6 +2530,7 @@
     template <typename Case>
     static void setupCallExpectations(DisplayTransactionTest* test) {
         Case::EventThread::setupAcquireAndEnableVsyncCallExpectations(test);
+        Case::DispSync::setupBeginResyncCallExpectations(test);
         Case::setupComposerCallExpectations(test, IComposerClient::PowerMode::ON);
     }
 };
@@ -2512,6 +2540,7 @@
     template <typename Case>
     static void setupCallExpectations(DisplayTransactionTest* test) {
         Case::EventThread::setupReleaseAndDisableVsyncCallExpectations(test);
+        Case::DispSync::setupEndResyncCallExpectations(test);
         Case::setupComposerCallExpectations(test, Case::Doze::ACTUAL_POWER_MODE_FOR_DOZE_SUSPEND);
     }
 };
@@ -2534,11 +2563,12 @@
 // --------------------------------------------------------------------
 
 template <typename DisplayVariant, typename DozeVariant, typename EventThreadVariant,
-          typename TransitionVariant>
+          typename DispSyncVariant, typename TransitionVariant>
 struct DisplayPowerCase {
     using Display = DisplayVariant;
     using Doze = DozeVariant;
     using EventThread = EventThreadVariant;
+    using DispSync = DispSyncVariant;
     using Transition = TransitionVariant;
 
     static auto injectDisplayWithInitialPowerMode(DisplayTransactionTest* test, int mode) {
@@ -2586,15 +2616,16 @@
 // In addition to having event thread support, we emulate doze support.
 template <typename TransitionVariant>
 using PrimaryDisplayPowerCase = DisplayPowerCase<PrimaryDisplayVariant, DozeIsSupportedVariant,
-                                                 EventThreadIsSupportedVariant, TransitionVariant>;
+                                                 EventThreadIsSupportedVariant,
+                                                 DispSyncIsSupportedVariant, TransitionVariant>;
 
 // A sample configuration for the external display.
 // In addition to not having event thread support, we emulate not having doze
 // support.
 template <typename TransitionVariant>
-using ExternalDisplayPowerCase =
-        DisplayPowerCase<ExternalDisplayVariant, DozeNotSupportedVariant,
-                         EventThreadNotSupportedVariant, TransitionVariant>;
+using ExternalDisplayPowerCase = DisplayPowerCase<ExternalDisplayVariant, DozeNotSupportedVariant,
+                                                  EventThreadNotSupportedVariant,
+                                                  DispSyncNotSupportedVariant, TransitionVariant>;
 
 class SetPowerModeInternalTest : public DisplayTransactionTest {
 public:
diff --git a/services/surfaceflinger/tests/unittests/TestableSurfaceFlinger.h b/services/surfaceflinger/tests/unittests/TestableSurfaceFlinger.h
index 5031148..9df4264 100644
--- a/services/surfaceflinger/tests/unittests/TestableSurfaceFlinger.h
+++ b/services/surfaceflinger/tests/unittests/TestableSurfaceFlinger.h
@@ -126,6 +126,7 @@
     auto& mutableInterceptor() { return mFlinger->mInterceptor; }
     auto& mutableMainThreadId() { return mFlinger->mMainThreadId; }
     auto& mutablePendingHotplugEvents() { return mFlinger->mPendingHotplugEvents; }
+    auto& mutablePrimaryDispSync() { return mFlinger->mPrimaryDispSync; }
     auto& mutablePrimaryHWVsyncEnabled() { return mFlinger->mPrimaryHWVsyncEnabled; }
     auto& mutableTransactionFlags() { return mFlinger->mTransactionFlags; }
     auto& mutableUseHwcVirtualDisplays() { return mFlinger->mUseHwcVirtualDisplays; }
@@ -144,6 +145,7 @@
         mutableEventQueue().reset();
         mutableEventThread().reset();
         mutableInterceptor().reset();
+        mutablePrimaryDispSync().reset();
         mFlinger->getBE().mHwc.reset();
         mFlinger->getBE().mRenderEngine.reset();
     }
diff --git a/services/surfaceflinger/tests/unittests/mock/MockDispSync.cpp b/services/surfaceflinger/tests/unittests/mock/MockDispSync.cpp
new file mode 100644
index 0000000..2f7e5ea
--- /dev/null
+++ b/services/surfaceflinger/tests/unittests/mock/MockDispSync.cpp
@@ -0,0 +1,27 @@
+/*
+ * Copyright (C) 2018 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 "mock/MockDispSync.h"
+
+namespace android {
+namespace mock {
+
+// Explicit default instantiation is recommended.
+DispSync::DispSync() = default;
+DispSync::~DispSync() = default;
+
+} // namespace mock
+} // namespace android
diff --git a/services/surfaceflinger/tests/unittests/mock/MockDispSync.h b/services/surfaceflinger/tests/unittests/mock/MockDispSync.h
new file mode 100644
index 0000000..4a466ef
--- /dev/null
+++ b/services/surfaceflinger/tests/unittests/mock/MockDispSync.h
@@ -0,0 +1,50 @@
+/*
+ * Copyright (C) 2018 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 <gmock/gmock.h>
+
+#include <utils/String8.h>
+#include "DispSync.h"
+
+namespace android {
+namespace mock {
+
+class DispSync : public android::DispSync {
+public:
+    DispSync();
+    ~DispSync() override;
+
+    MOCK_METHOD0(reset, void());
+    MOCK_METHOD1(addPresentFence, bool(const std::shared_ptr<FenceTime>&));
+    MOCK_METHOD0(beginResync, void());
+    MOCK_METHOD1(addResyncSample, bool(nsecs_t));
+    MOCK_METHOD0(endResync, void());
+    MOCK_METHOD1(setPeriod, void(nsecs_t));
+    MOCK_METHOD0(getPeriod, nsecs_t());
+    MOCK_METHOD1(setRefreshSkipCount, void(int));
+    MOCK_METHOD3(addEventListener, status_t(const char*, nsecs_t, Callback*));
+    MOCK_METHOD1(removeEventListener, status_t(Callback*));
+    MOCK_METHOD2(changePhaseOffset, status_t(Callback*, nsecs_t));
+    MOCK_CONST_METHOD1(computeNextRefresh, nsecs_t(int));
+    MOCK_METHOD1(setIgnorePresentFences, void(bool));
+
+    MOCK_CONST_METHOD1(dump, void(String8&));
+};
+
+} // namespace mock
+} // namespace android