Plumb preferred raster scale for background images from Blink to cc layers.

third_party/WebKit/Source/platform/graphics/GraphicsLayer.h

 /*
  * Copyright (C) 2009 Apple Inc. All rights reserved.
  * Copyright (C) 2013 Intel Corporation. All rights reserved.
  *
  * Redistribution and use in source and binary forms, with or without
  * modification, are permitted provided that the following conditions
  * are met:
  * 1. Redistributions of source code must retain the above copyright
  *    notice, this list of conditions and the following disclaimer.
  * 2. Redistributions in binary form must reproduce the above copyright
@@ skipping 260 matching lines @@
   ContentLayerDelegate* contentLayerDelegateForTesting() const {
     return m_contentLayerDelegate.get();
   }
 
   // DisplayItemClient methods
   String debugName() const final { return m_client->debugName(this); }
   LayoutRect visualRect() const override;
 
   void setHasWillChangeTransformHint(bool);
 
+  void setPreferredRasterScale(float);
+  void clearPreferredRasterScale();
+
  protected:
   String debugName(cc::Layer*) const;
   bool shouldFlattenTransform() const { return m_shouldFlattenTransform; }
 
   explicit GraphicsLayer(GraphicsLayerClient*);
   // for testing
   friend class CompositedLayerMappingTest;
   friend class PaintControllerPaintTestBase;
 
  private:
@@ skipping 97 matching lines @@
 
   std::unique_ptr<ContentLayerDelegate> m_contentLayerDelegate;
 
   WeakPersistent<ScrollableArea> m_scrollableArea;
   GraphicsLayerDebugInfo m_debugInfo;
   int m_renderingContext3d;
 
   std::unique_ptr<PaintController> m_paintController;
 
   IntRect m_previousInterestRect;
+  float m_preferredRasterScale;
+  bool m_hasPreferredRasterScale;
 };
 
 }  // namespace blink
 
 #ifndef NDEBUG
 // Outside the blink namespace for ease of invocation from gdb.
 void PLATFORM_EXPORT showGraphicsLayerTree(const blink::GraphicsLayer*);
 #endif
 
 #endif  // GraphicsLayer_h