cc: Avoid expensive RenderingStats collection.

cc/caching_bitmap_content_layer_updater.h

 // Copyright 2012 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #ifndef CC_CACHING_BITMAP_CONTENT_LAYER_UPDATER_H_
 #define CC_CACHING_BITMAP_CONTENT_LAYER_UPDATER_H_
 
 #include "base/compiler_specific.h"
 #include "cc/bitmap_content_layer_updater.h"
 #include "third_party/skia/include/core/SkBitmap.h"
 
 namespace cc {
 
 class CachingBitmapContentLayerUpdater
     : public BitmapContentLayerUpdater {
  public:
   static scoped_refptr<CachingBitmapContentLayerUpdater> Create(
       scoped_ptr<LayerPainter>);
 
   virtual void prepareToUpdate(const gfx::Rect& content_rect,
                                const gfx::Size& tile_size,
                                float contents_width_scale,
                                float contents_height_scale,
                                gfx::Rect& resulting_opaque_rect,
-                               RenderingStats&) OVERRIDE;
+                               RenderingStats*) OVERRIDE;
 
   bool pixelsDidChange() const;
 
  private:
   explicit CachingBitmapContentLayerUpdater(
       scoped_ptr<LayerPainter> painter);
   virtual ~CachingBitmapContentLayerUpdater();
 
   bool pixels_did_change_;
   SkBitmap cached_bitmap_;
 };
 
 }  // namespace cc
 
 #endif  // CC_CACHING_BITMAP_CONTENT_LAYER_UPDATER_H_