cc: Use maximum tiling contents scales for picture layer scale

cc/picture_layer_impl.h

 // Copyright 2012 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_LAYER_IMPL_H_
 #define CC_PICTURE_LAYER_IMPL_H_
 
 #include "cc/layer_impl.h"
 #include "cc/picture_layer_tiling.h"
 #include "cc/picture_layer_tiling_set.h"
@@ skipping 12 matching lines @@
   {
       return make_scoped_ptr(new PictureLayerImpl(treeImpl, id));
   }
   virtual ~PictureLayerImpl();
 
   // LayerImpl overrides.
   virtual const char* layerTypeAsString() const OVERRIDE;
   virtual void appendQuads(QuadSink&, AppendQuadsData&) OVERRIDE;
   virtual void dumpLayerProperties(std::string*, int indent) const OVERRIDE;
   virtual void didUpdateTransforms() OVERRIDE;
+  virtual void calculateContentsScale(
+      float ideal_contents_scale,
+      float* contents_scale_x,
+      float* contents_scale_y,
+      gfx::Size* content_bounds) OVERRIDE;
 
   // PictureLayerTilingClient overrides.
   virtual scoped_refptr<Tile> CreateTile(PictureLayerTiling*,
                                          gfx::Rect) OVERRIDE;
 
   // PushPropertiesTo active tree => pending tree
   void SyncFromActiveLayer();
   void SyncTiling(const PictureLayerTiling* tiling);
 
   // Mask-related functions
   void SetIsMask(bool is_mask);
   virtual ResourceProvider::ResourceId contentsResourceId() const OVERRIDE;
 
 protected:
   PictureLayerImpl(LayerTreeImpl* treeImpl, int id);
   void AddTiling(float contents_scale, gfx::Size tile_size);
   void SyncFromActiveLayer(const PictureLayerImpl* other);
   gfx::Size TileSize() const;
+  void ManageTilings(float ideal_contents_scale);
 
   PictureLayerTilingSet tilings_;
   scoped_refptr<PicturePileImpl> pile_;
   Region invalidation_;
 
   gfx::Transform last_screen_space_transform_;
   double last_update_time_;
   gfx::Size last_bounds_;
   gfx::Size last_content_bounds_;
   float last_content_scale_x_;
   float last_content_scale_y_;
   bool is_mask_;
 
   friend class PictureLayer;
   DISALLOW_COPY_AND_ASSIGN(PictureLayerImpl);
 };
 
 }
 
 #endif  // CC_PICTURE_LAYER_IMPL_H_