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

cc/layers/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_LAYER_H_
 #define CC_LAYERS_LAYER_H_
 
 #include <stddef.h>
 #include <stdint.h>
 
@@ skipping 460 matching lines @@
   void SetMutableProperties(uint32_t properties);
   uint32_t mutable_properties() const { return inputs_.mutable_properties; }
 
   bool HasActiveAnimationForTesting() const;
 
   void SetHasWillChangeTransformHint(bool has_will_change);
   bool has_will_change_transform_hint() const {
     return inputs_.has_will_change_transform_hint;
   }
 
+  void SetPreferredRasterScale(float preferred_raster_scale);
+  bool has_preferred_raster_scale() {
+    return inputs_.has_preferred_raster_scale;
+  }
+  float preferred_raster_scale() const {
+    return inputs_.preferred_raster_scale;
+  }
+  void ClearPreferredRasterScale();
+
   AnimationHost* GetAnimationHost() const;
 
   ElementListType GetElementTypeForAnimation() const;
 
   // Tests in remote mode need to explicitly set the layer id so it matches the
   // layer id for the corresponding Layer on the engine.
   void SetLayerIdForTesting(int id);
 
  protected:
   friend class LayerImpl;
@@ skipping 173 matching lines @@
     LayerStickyPositionConstraint sticky_position_constraint;
 
     ElementId element_id;
 
     uint32_t mutable_properties;
 
     Layer* scroll_parent;
     Layer* clip_parent;
 
     bool has_will_change_transform_hint : 1;
+    bool has_preferred_raster_scale : 1;
 
     bool hide_layer_and_subtree : 1;
 
     // The following elements can not and are not serialized.
     LayerClient* client;
     base::Closure did_scroll_callback;
     std::vector<std::unique_ptr<CopyOutputRequest>> copy_requests;
+
+    float preferred_raster_scale;
   };
 
   Layer* parent_;
 
   // Layer instances have a weak pointer to their LayerTreeHost.
   // This pointer value is nil when a Layer is not in a tree and is
   // updated via SetLayerTreeHost() if a layer moves between trees.
   LayerTreeHost* layer_tree_host_;
   LayerTree* layer_tree_;
 
@@ skipping 26 matching lines @@
   // These all act like draw properties, so don't need push properties.
   gfx::Rect visible_layer_rect_;
   size_t num_unclipped_descendants_;
 
   DISALLOW_COPY_AND_ASSIGN(Layer);
 };
 
 }  // namespace cc
 
 #endif  // CC_LAYERS_LAYER_H_