cc: Avoid expensive RenderingStats collection.

cc/layer_updater.h

Index: cc/layer_updater.h
diff --git a/cc/layer_updater.h b/cc/layer_updater.h
index 5ee4a2c84b5964f3461aaa5361aba8d19ebb4842..ee2287ee40146013772cf41de839b3dcd84c0105 100644
--- a/cc/layer_updater.h
+++ b/cc/layer_updater.h
@@ -34,7 +34,7 @@ public:
         void swapTextureWith(scoped_ptr<PrioritizedResource>& texture);
         // TODO(reveman): partialUpdate should be a property of this class
         // instead of an argument passed to update().
-        virtual void update(ResourceUpdateQueue&, const gfx::Rect& sourceRect, const gfx::Vector2d& destOffset, bool partialUpdate, RenderingStats&) = 0;
+        virtual void update(ResourceUpdateQueue&, const gfx::Rect& sourceRect, const gfx::Vector2d& destOffset, bool partialUpdate, RenderingStats*) = 0;
     protected:
         explicit Resource(scoped_ptr<PrioritizedResource> texture);
 
@@ -49,7 +49,7 @@ public:
     virtual scoped_ptr<Resource> createResource(PrioritizedResourceManager*) = 0;
     // The |resultingOpaqueRect| gives back a region of the layer that was painted opaque. If the layer is marked opaque in the updater,
     // then this region should be ignored in preference for the entire layer's area.
-    virtual void prepareToUpdate(const gfx::Rect& contentRect, const gfx::Size& tileSize, float contentsWidthScale, float contentsHeightScale, gfx::Rect& resultingOpaqueRect, RenderingStats&) { }
+    virtual void prepareToUpdate(const gfx::Rect& contentRect, const gfx::Size& tileSize, float contentsWidthScale, float contentsHeightScale, gfx::Rect& resultingOpaqueRect, RenderingStats*) { }
 
     // Set true by the layer when it is known that the entire output is going to be opaque.
     virtual void setOpaque(bool) { }