Efficiently handle image layer scaling

cc/picture_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_PICTURE_IMAGE_LAYER_H_
 #define CC_PICTURE_IMAGE_LAYER_H_
 
 #include "cc/cc_export.h"
 #include "cc/content_layer_client.h"
 #include "cc/picture_layer.h"
 #include "third_party/skia/include/core/SkBitmap.h"
 #include "ui/gfx/size.h"
 
 namespace cc {
 
 class CC_EXPORT PictureImageLayer : public PictureLayer, ContentLayerClient {
  public:
   static scoped_refptr<PictureImageLayer> create();
 
   void setBitmap(const SkBitmap& image);
 
   // Layer implementation.
-  virtual void update(
-      ResourceUpdateQueue& queue,
-      const OcclusionTracker* tracker,
-      RenderingStats* stats) OVERRIDE;
+  virtual scoped_ptr<LayerImpl> createLayerImpl(
+      LayerTreeImpl* treeImpl) OVERRIDE;
+  virtual bool drawsContent() const OVERRIDE;
 
   // ContentLayerClient implementation.
   virtual void paintContents(
       SkCanvas* canvas,
       const gfx::Rect& clip,
       gfx::RectF& opaque) OVERRIDE;
 
  private:
   PictureImageLayer();
   virtual ~PictureImageLayer();
 
   SkBitmap bitmap_;
-  gfx::Size bounds_;
 };
 
 }  // namespace cc
 
 #endif  // CC_PICTURE_IMAGE_LAYER_H_