Turn off computation of the interest rect in cc in synchronized paint mode.

cc/layers/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_LAYERS_PICTURE_IMAGE_LAYER_H_
 #define CC_LAYERS_PICTURE_IMAGE_LAYER_H_
 
 #include "cc/base/cc_export.h"
 #include "cc/layers/content_layer_client.h"
 #include "cc/layers/picture_layer.h"
 #include "skia/ext/refptr.h"
 #include "ui/gfx/geometry/size.h"
 
 class SkImage;
 
 namespace cc {
 
 class CC_EXPORT PictureImageLayer : public PictureLayer, ContentLayerClient {
  public:
   static scoped_refptr<PictureImageLayer> Create(const LayerSettings& settings);
 
   void SetImage(skia::RefPtr<const SkImage> image);
 
   // Layer implementation.
   scoped_ptr<LayerImpl> CreateLayerImpl(LayerTreeImpl* tree_impl) override;
 
+  gfx::Rect PaintableRegion() override;
+
   // ContentLayerClient implementation.
   scoped_refptr<DisplayItemList> PaintContentsToDisplayList(
       const gfx::Rect& clip,
       ContentLayerClient::PaintingControlSetting painting_control) override;
   bool FillsBoundsCompletely() const override;
   size_t GetApproximateUnsharedMemoryUsage() const override;
 
  protected:
   bool HasDrawableContent() const override;
 
  private:
   explicit PictureImageLayer(const LayerSettings& settings);
   ~PictureImageLayer() override;
 
   skia::RefPtr<const SkImage> image_;
 
   DISALLOW_COPY_AND_ASSIGN(PictureImageLayer);
 };
 
 }  // namespace cc
 
 #endif  // CC_LAYERS_PICTURE_IMAGE_LAYER_H_