[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/SurfaceFlinger.cpp b/services/surfaceflinger/SurfaceFlinger.cpp
index 29fe5d9..bbb07a8 100644
--- a/services/surfaceflinger/SurfaceFlinger.cpp
+++ b/services/surfaceflinger/SurfaceFlinger.cpp
@@ -990,6 +990,9 @@
         return;
     }
 
+    auto& oldRefreshRate =
+            mRefreshRateConfigs->getRefreshRateFromConfigId(display->getActiveConfig());
+
     std::lock_guard<std::mutex> lock(mActiveConfigLock);
     mRefreshRateConfigs->setCurrentConfigId(mUpcomingActiveConfig.configId);
     mRefreshRateStats->setConfigMode(mUpcomingActiveConfig.configId);
@@ -997,6 +1000,9 @@
 
     auto& refreshRate =
             mRefreshRateConfigs->getRefreshRateFromConfigId(mUpcomingActiveConfig.configId);
+    if (refreshRate.vsyncPeriod != oldRefreshRate.vsyncPeriod) {
+        mTimeStats->incrementRefreshRateSwitches();
+    }
     mPhaseConfiguration->setRefreshRateFps(refreshRate.fps);
     mVSyncModulator->setPhaseOffsets(mPhaseConfiguration->getCurrentOffsets());
     ATRACE_INT("ActiveConfigFPS", refreshRate.fps);