Revert of [#7] Pass gfx structs by const ref (gfx::Size)

cc/resources/tile_manager.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_RESOURCES_TILE_MANAGER_H_
 #define CC_RESOURCES_TILE_MANAGER_H_
 
 #include <queue>
 #include <set>
 #include <vector>
@@ skipping 48 matching lines @@
       size_t max_raster_usage_bytes,
       unsigned map_image_texture_target);
   virtual ~TileManager();
 
   void ManageTiles(const GlobalStateThatImpactsTilePriority& state);
 
   // Returns true when visible tiles have been initialized.
   bool UpdateVisibleTiles();
 
   scoped_refptr<Tile> CreateTile(PicturePileImpl* picture_pile,
-                                 const gfx::Size& tile_size,
+                                 gfx::Size tile_size,
                                  const gfx::Rect& content_rect,
                                  const gfx::Rect& opaque_rect,
                                  float contents_scale,
                                  int layer_id,
                                  int source_frame_number,
                                  int flags);
 
   scoped_ptr<base::Value> BasicStateAsValue() const;
   scoped_ptr<base::Value> AllTilesAsValue() const;
   void GetMemoryStats(size_t* memory_required_bytes,
@@ skipping 131 matching lines @@
   RasterTaskCompletionStats update_visible_tiles_stats_;
 
   std::vector<Tile*> released_tiles_;
 
   DISALLOW_COPY_AND_ASSIGN(TileManager);
 };
 
 }  // namespace cc
 
 #endif  // CC_RESOURCES_TILE_MANAGER_H_