[SurfaceFlinger] Add refresh rate counts to TimeStats

This count will be exposed to lab tests as a breakdown metric for
uncovering jank.

Bug: 144526027
Test: dumpsys SurfaceFlinger --timestats -dump
Test: libsurfaceflinger_unittest
Change-Id: I921e147e96212ad6a08fa14d6e3d7a98893a8602
diff --git a/services/surfaceflinger/TimeStats/TimeStats.cpp b/services/surfaceflinger/TimeStats/TimeStats.cpp
index 8038eba..96fd03a 100644
--- a/services/surfaceflinger/TimeStats/TimeStats.cpp
+++ b/services/surfaceflinger/TimeStats/TimeStats.cpp
@@ -282,6 +282,15 @@
     mTimeStats.clientCompositionReusedFrames++;
 }
 
+void TimeStats::incrementRefreshRateSwitches() {
+    if (!mEnabled.load()) return;
+
+    ATRACE_CALL();
+
+    std::lock_guard<std::mutex> lock(mMutex);
+    mTimeStats.refreshRateSwitches++;
+}
+
 void TimeStats::recordDisplayEventConnectionCount(int32_t count) {
     if (!mEnabled.load()) return;
 
@@ -835,6 +844,7 @@
     mTimeStats.missedFrames = 0;
     mTimeStats.clientCompositionFrames = 0;
     mTimeStats.clientCompositionReusedFrames = 0;
+    mTimeStats.refreshRateSwitches = 0;
     mTimeStats.displayEventConnectionsCount = 0;
     mTimeStats.displayOnTime = 0;
     mTimeStats.presentToPresent.hist.clear();
diff --git a/services/surfaceflinger/TimeStats/TimeStats.h b/services/surfaceflinger/TimeStats/TimeStats.h
index ddebeb1..8bbae1f 100644
--- a/services/surfaceflinger/TimeStats/TimeStats.h
+++ b/services/surfaceflinger/TimeStats/TimeStats.h
@@ -52,6 +52,8 @@
     virtual void incrementMissedFrames() = 0;
     virtual void incrementClientCompositionFrames() = 0;
     virtual void incrementClientCompositionReusedFrames() = 0;
+    // Increments the number of times the display refresh rate changed.
+    virtual void incrementRefreshRateSwitches() = 0;
     // Records the most up-to-date count of display event connections.
     // The stored count will be the maximum ever recoded.
     virtual void recordDisplayEventConnectionCount(int32_t count) = 0;
@@ -215,6 +217,7 @@
     void incrementMissedFrames() override;
     void incrementClientCompositionFrames() override;
     void incrementClientCompositionReusedFrames() override;
+    void incrementRefreshRateSwitches() override;
     void recordDisplayEventConnectionCount(int32_t count) override;
 
     void recordFrameDuration(nsecs_t startTime, nsecs_t endTime) override;
diff --git a/services/surfaceflinger/TimeStats/timestatsproto/TimeStatsHelper.cpp b/services/surfaceflinger/TimeStats/timestatsproto/TimeStatsHelper.cpp
index e2f85cc..5305de9 100644
--- a/services/surfaceflinger/TimeStats/timestatsproto/TimeStatsHelper.cpp
+++ b/services/surfaceflinger/TimeStats/timestatsproto/TimeStatsHelper.cpp
@@ -105,6 +105,7 @@
     StringAppendF(&result, "missedFrames = %d\n", missedFrames);
     StringAppendF(&result, "clientCompositionFrames = %d\n", clientCompositionFrames);
     StringAppendF(&result, "clientCompositionReusedFrames = %d\n", clientCompositionReusedFrames);
+    StringAppendF(&result, "refreshRateSwitches = %d\n", refreshRateSwitches);
     StringAppendF(&result, "displayOnTime = %" PRId64 " ms\n", displayOnTime);
     StringAppendF(&result, "displayConfigStats is as below:\n");
     for (const auto& [fps, duration] : refreshRateStats) {
diff --git a/services/surfaceflinger/TimeStats/timestatsproto/include/timestatsproto/TimeStatsHelper.h b/services/surfaceflinger/TimeStats/timestatsproto/include/timestatsproto/TimeStatsHelper.h
index 5e7c449..afb98e0 100644
--- a/services/surfaceflinger/TimeStats/timestatsproto/include/timestatsproto/TimeStatsHelper.h
+++ b/services/surfaceflinger/TimeStats/timestatsproto/include/timestatsproto/TimeStatsHelper.h
@@ -62,6 +62,7 @@
         int32_t missedFrames = 0;
         int32_t clientCompositionFrames = 0;
         int32_t clientCompositionReusedFrames = 0;
+        int32_t refreshRateSwitches = 0;
         int32_t displayEventConnectionsCount = 0;
         int64_t displayOnTime = 0;
         Histogram presentToPresent;