cc: Avoid expensive RenderingStats collection.

cc/image_layer.h

 // Copyright 2010 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_IMAGE_LAYER_H_
 #define CC_IMAGE_LAYER_H_
 
 #include "cc/cc_export.h"
 #include "cc/content_layer.h"
 #include "third_party/skia/include/core/SkBitmap.h"
 
 namespace cc {
 
 class ImageLayerUpdater;
 
 // A Layer that contains only an Image element.
 class CC_EXPORT ImageLayer : public TiledLayer {
 public:
     static scoped_refptr<ImageLayer> create();
 
     virtual bool drawsContent() const OVERRIDE;
     virtual void setTexturePriorities(const PriorityCalculator&) OVERRIDE;
-    virtual void update(ResourceUpdateQueue&, const OcclusionTracker*, RenderingStats&) OVERRIDE;
+    virtual void update(ResourceUpdateQueue&, const OcclusionTracker*, RenderingStats*) OVERRIDE;
     virtual void calculateContentsScale(
         float idealContentsScale,
         float* contentsScaleX,
         float* contentsScaleY,
         gfx::Size* contentBounds) OVERRIDE;
 
     void setBitmap(const SkBitmap& image);
 
 private:
     ImageLayer();
     virtual ~ImageLayer();
 
     void setTilingOption(TilingOption);
 
     virtual LayerUpdater* updater() const OVERRIDE;
     virtual void createUpdaterIfNeeded() OVERRIDE;
     float imageContentsScaleX() const;
     float imageContentsScaleY() const;
 
     SkBitmap m_bitmap;
 
     scoped_refptr<ImageLayerUpdater> m_updater;
 };
 
 }  // namespace cc
 
 #endif  // CC_IMAGE_LAYER_H_