SF: VSyncTracker, clear timestamps on beginResync

DispSync would clear its internal model around power events, as the
vsync timings during power mode changes are not accurate for screen-on
vsync prediction. DispSync uses the beginResync signal for this, and the
new system does the same (although once DispSync is deprecated,
begin/endResync should go away too).

Fixes: 146050690
Test: Dogfooding blueline
Test: 2 new unit tests
Change-Id: Ie4b607029516dcea0e5d65afca75a7017bf63e12
diff --git a/services/surfaceflinger/tests/unittests/VSyncDispatchRealtimeTest.cpp b/services/surfaceflinger/tests/unittests/VSyncDispatchRealtimeTest.cpp
index 5846c77..9c3d32e 100644
--- a/services/surfaceflinger/tests/unittests/VSyncDispatchRealtimeTest.cpp
+++ b/services/surfaceflinger/tests/unittests/VSyncDispatchRealtimeTest.cpp
@@ -50,6 +50,7 @@
     nsecs_t currentPeriod() const final { return mPeriod; }
 
     void setPeriod(nsecs_t) final {}
+    void resetModel() final {}
 
 private:
     nsecs_t const mPeriod;
@@ -83,6 +84,7 @@
     }
 
     void setPeriod(nsecs_t) final {}
+    void resetModel() final {}
 
 private:
     std::mutex mutable mMutex;
diff --git a/services/surfaceflinger/tests/unittests/VSyncDispatchTimerQueueTest.cpp b/services/surfaceflinger/tests/unittests/VSyncDispatchTimerQueueTest.cpp
index 5aff429..b23159b 100644
--- a/services/surfaceflinger/tests/unittests/VSyncDispatchTimerQueueTest.cpp
+++ b/services/surfaceflinger/tests/unittests/VSyncDispatchTimerQueueTest.cpp
@@ -41,6 +41,7 @@
     MOCK_CONST_METHOD1(nextAnticipatedVSyncTimeFrom, nsecs_t(nsecs_t));
     MOCK_CONST_METHOD0(currentPeriod, nsecs_t());
     MOCK_METHOD1(setPeriod, void(nsecs_t));
+    MOCK_METHOD0(resetModel, void());
 
     nsecs_t nextVSyncTime(nsecs_t timePoint) const {
         if (timePoint % mPeriod == 0) {
diff --git a/services/surfaceflinger/tests/unittests/VSyncPredictorTest.cpp b/services/surfaceflinger/tests/unittests/VSyncPredictorTest.cpp
index 4cb6a38..afa1481 100644
--- a/services/surfaceflinger/tests/unittests/VSyncPredictorTest.cpp
+++ b/services/surfaceflinger/tests/unittests/VSyncPredictorTest.cpp
@@ -351,4 +351,19 @@
     EXPECT_THAT(prediction, Ge(timePoint));
 }
 
+TEST_F(VSyncPredictorTest, resetsWhenInstructed) {
+    auto const idealPeriod = 10000;
+    auto const realPeriod = 10500;
+    tracker.setPeriod(idealPeriod);
+    for (auto i = 0; i < kMinimumSamplesForPrediction; i++) {
+        tracker.addVsyncTimestamp(i * realPeriod);
+    }
+
+    EXPECT_THAT(std::get<0>(tracker.getVSyncPredictionModel()),
+                IsCloseTo(realPeriod, mMaxRoundingError));
+    tracker.resetModel();
+    EXPECT_THAT(std::get<0>(tracker.getVSyncPredictionModel()),
+                IsCloseTo(idealPeriod, mMaxRoundingError));
+}
+
 } // namespace android::scheduler
diff --git a/services/surfaceflinger/tests/unittests/VSyncReactorTest.cpp b/services/surfaceflinger/tests/unittests/VSyncReactorTest.cpp
index 72f8bb9..d5e0660 100644
--- a/services/surfaceflinger/tests/unittests/VSyncReactorTest.cpp
+++ b/services/surfaceflinger/tests/unittests/VSyncReactorTest.cpp
@@ -39,6 +39,7 @@
     MOCK_CONST_METHOD1(nextAnticipatedVSyncTimeFrom, nsecs_t(nsecs_t));
     MOCK_CONST_METHOD0(currentPeriod, nsecs_t());
     MOCK_METHOD1(setPeriod, void(nsecs_t));
+    MOCK_METHOD0(resetModel, void());
 };
 
 class VSyncTrackerWrapper : public VSyncTracker {
@@ -50,7 +51,8 @@
         return mTracker->nextAnticipatedVSyncTimeFrom(timePoint);
     }
     nsecs_t currentPeriod() const final { return mTracker->currentPeriod(); }
-    void setPeriod(nsecs_t period) { mTracker->setPeriod(period); }
+    void setPeriod(nsecs_t period) final { mTracker->setPeriod(period); }
+    void resetModel() final { mTracker->resetModel(); }
 
 private:
     std::shared_ptr<VSyncTracker> const mTracker;
@@ -515,6 +517,11 @@
     mReactor.addEventListener(mName, negativePhase, &outerCb, lastCallbackTime);
 }
 
+TEST_F(VSyncReactorTest, beginResyncResetsModel) {
+    EXPECT_CALL(*mMockTracker, resetModel());
+    mReactor.beginResync();
+}
+
 using VSyncReactorDeathTest = VSyncReactorTest;
 TEST_F(VSyncReactorDeathTest, invalidRemoval) {
     mReactor.addEventListener(mName, mPhase, &outerCb, lastCallbackTime);