Add average commit time to perf tests.

cc/CCSingleThreadProxy.h

Index: cc/CCSingleThreadProxy.h
diff --git a/cc/CCSingleThreadProxy.h b/cc/CCSingleThreadProxy.h
index 8e0594c96d07b3528808f4d428fd2fcb5c60e100..4a9278ea259ff33396ae68f317f92c65a2a46170 100644
--- a/cc/CCSingleThreadProxy.h
+++ b/cc/CCSingleThreadProxy.h
@@ -8,6 +8,7 @@
 #include "CCAnimationEvents.h"
 #include "CCLayerTreeHostImpl.h"
 #include "CCProxy.h"
+#include <base/time.h>
 #include <limits>
 #include <wtf/OwnPtr.h>
 
@@ -30,7 +31,7 @@ public:
     virtual void setVisible(bool) OVERRIDE;
     virtual bool initializeRenderer() OVERRIDE;
     virtual bool recreateContext() OVERRIDE;
-    virtual void implSideRenderingStats(CCRenderingStats&) OVERRIDE;
+    virtual void renderingStats(CCRenderingStats*) OVERRIDE;
     virtual const RendererCapabilities& rendererCapabilities() const OVERRIDE;
     virtual void loseContext() OVERRIDE;
     virtual void setNeedsAnimate() OVERRIDE;
@@ -79,6 +80,9 @@ private:
     RendererCapabilities m_RendererCapabilitiesForMainThread;
 
     bool m_nextFrameIsNewlyCommittedFrame;
+
+    base::TimeDelta m_totalCommitTime;
+    size_t m_totalCommitCount;
 };
 
 // For use in the single-threaded case. In debug builds, it pretends that the