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

cc/layer_tree_host.h

Index: cc/layer_tree_host.h
diff --git a/cc/layer_tree_host.h b/cc/layer_tree_host.h
index dc5aeaf3affcaebb2227afd6c0c92a7c7078070a..af20156bec306f54cbc7cf248d868b01689833df 100644
--- a/cc/layer_tree_host.h
+++ b/cc/layer_tree_host.h
@@ -47,6 +47,7 @@ class PrioritizedTextureManager;
 class ResourceUpdateQueue;
 class HeadsUpDisplayLayer;
 class Region;
+class RenderingStatsSubscriber;
 struct ScrollAndScaleSet;
 
 struct LayerTreeSettings {
@@ -198,6 +199,11 @@ public:
     void startRateLimiter(WebKit::WebGraphicsContext3D*);
     void stopRateLimiter(WebKit::WebGraphicsContext3D*);
 
+    void startRecordingRenderingStats();
+    // This function will remove the running subscriber, and populate the given
+    // rendering stats object.
+    void stopRecordingRenderingStats(RenderingStats*);
+
     // RateLimitClient implementation
     virtual void rateLimit() OVERRIDE;
 
@@ -244,7 +250,9 @@ private:
     LayerTreeHostClient* m_client;
 
     int m_commitNumber;
+    // TODO(vollick): Nuke this once we've switched to the subscriber model.
     RenderingStats m_renderingStats;
+    scoped_ptr<RenderingStatsSubscriber> m_renderingStatsSubscriber;
 
     scoped_ptr<Proxy> m_proxy;
     bool m_rendererInitialized;