[#2] Pass gfx structs by const ref (gfx::Rect, gfx::RectF)

cc/resources/layer_tiling_data.h

 // Copyright 2011 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_LAYER_TILING_DATA_H_
 #define CC_RESOURCES_LAYER_TILING_DATA_H_
 
 #include <utility>
 
 #include "base/basictypes.h"
@@ skipping 46 matching lines @@
     virtual ~Tile() {}
 
     int i() const { return i_; }
     int j() const { return j_; }
     void move_to(int i, int j) {
       i_ = i;
       j_ = j;
     }
 
     gfx::Rect opaque_rect() const { return opaque_rect_; }
-    void set_opaque_rect(gfx::Rect opaque_rect) { opaque_rect_ = opaque_rect; }
+    void set_opaque_rect(const gfx::Rect& opaque_rect) {
+      opaque_rect_ = opaque_rect;
+    }
    private:
     int i_;
     int j_;
     gfx::Rect opaque_rect_;
     DISALLOW_COPY_AND_ASSIGN(Tile);
   };
   typedef std::pair<int, int> TileMapKey;
   typedef base::ScopedPtrHashMap<TileMapKey, Tile> TileMap;
 
   void AddTile(scoped_ptr<Tile> tile, int i, int j);
   scoped_ptr<Tile> TakeTile(int i, int j);
   Tile* TileAt(int i, int j) const;
   const TileMap& tiles() const { return tiles_; }
 
   void SetBounds(gfx::Size size);
   gfx::Size bounds() const { return tiling_data_.total_size(); }
 
-  void ContentRectToTileIndices(gfx::Rect rect,
+  void ContentRectToTileIndices(const gfx::Rect& rect,
                                 int* left,
                                 int* top,
                                 int* right,
                                 int* bottom) const;
   gfx::Rect TileRect(const Tile* tile) const;
 
-  Region OpaqueRegionInContentRect(gfx::Rect rect) const;
+  Region OpaqueRegionInContentRect(const gfx::Rect& rect) const;
 
   void reset() { tiles_.clear(); }
 
  protected:
   LayerTilingData(gfx::Size tile_size, BorderTexelOption option);
 
   TileMap tiles_;
   TilingData tiling_data_;
 
   DISALLOW_COPY(LayerTilingData);
 };
 
 }  // namespace cc
 
 #endif  // CC_RESOURCES_LAYER_TILING_DATA_H_