NOT READY FOR REVIEW - switch to a subscriber model for rendering stats

cc/rendering_stats.h

Index: cc/rendering_stats.h
diff --git a/cc/rendering_stats.h b/cc/rendering_stats.h
index 96634986d70fe09ce3977bba411ba89f88fa565f..66be8965ea21bbe26eaa21880997ab49925956a3 100644
--- a/cc/rendering_stats.h
+++ b/cc/rendering_stats.h
@@ -12,6 +12,8 @@ struct RenderingStats {
     int numAnimationFrames;
     int numFramesSentToScreen;
     int droppedFrameCount;
+    double frameRateAverage;
+    double frameRateStandardDeviation;
     double totalPaintTimeInSeconds;
     double totalRasterizeTimeInSeconds;
     double totalCommitTimeInSeconds;
@@ -19,20 +21,9 @@ struct RenderingStats {
     size_t numImplThreadScrolls;
     size_t numMainThreadScrolls;
 
-    RenderingStats()
-        : numAnimationFrames(0)
-        , numFramesSentToScreen(0)
-        , droppedFrameCount(0)
-        , totalPaintTimeInSeconds(0)
-        , totalRasterizeTimeInSeconds(0)
-        , totalCommitTimeInSeconds(0)
-        , totalCommitCount(0)
-        , numImplThreadScrolls(0)
-        , numMainThreadScrolls(0)
-    {
-    }
+    RenderingStats();
 };
 
-}
+}  // namespace cc
 
 #endif