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

cc/layers/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_LAYERS_PICTURE_LAYER_IMPL_H_
 #define CC_LAYERS_PICTURE_LAYER_IMPL_H_
 
 #include <string>
 #include <vector>
 
@@ skipping 40 matching lines @@
                                       float* contents_scale_y,
                                       gfx::Size* content_bounds) OVERRIDE;
   virtual skia::RefPtr<SkPicture> GetPicture() OVERRIDE;
 
   // PictureLayerTilingClient overrides.
   virtual scoped_refptr<Tile> CreateTile(
     PictureLayerTiling* tiling,
     const gfx::Rect& content_rect) OVERRIDE;
   virtual void UpdatePile(Tile* tile) OVERRIDE;
   virtual gfx::Size CalculateTileSize(
-      const gfx::Size& content_bounds) const OVERRIDE;
+      gfx::Size content_bounds) const OVERRIDE;
   virtual const Region* GetInvalidation() OVERRIDE;
   virtual const PictureLayerTiling* GetTwinTiling(
       const PictureLayerTiling* tiling) const OVERRIDE;
 
   // PushPropertiesTo active tree => pending tree.
   void SyncTiling(const PictureLayerTiling* tiling);
 
   // Mask-related functions
   void SetIsMask(bool is_mask);
   virtual ResourceProvider::ResourceId ContentsResourceId() const OVERRIDE;
@@ skipping 79 matching lines @@
   bool should_update_tile_priorities_;
   bool should_use_gpu_rasterization_;
 
   friend class PictureLayer;
   DISALLOW_COPY_AND_ASSIGN(PictureLayerImpl);
 };
 
 }  // namespace cc
 
 #endif  // CC_LAYERS_PICTURE_LAYER_IMPL_H_