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

cc/resources/picture_layer_tiling_set.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_PICTURE_LAYER_TILING_SET_H_
 #define CC_RESOURCES_PICTURE_LAYER_TILING_SET_H_
 
 #include "cc/base/region.h"
 #include "cc/base/scoped_ptr_vector.h"
 #include "cc/resources/picture_layer_tiling.h"
@@ skipping 39 matching lines @@
 
   // Remove one tiling.
   void Remove(PictureLayerTiling* tiling);
 
   // Remove all tiles; keep all tilings.
   void RemoveAllTiles();
 
   void UpdateTilePriorities(
       WhichTree tree,
       gfx::Size device_viewport,
-      gfx::Rect viewport_in_content_space,
-      gfx::Rect visible_content_rect,
+      const gfx::Rect& viewport_in_content_space,
+      const gfx::Rect& visible_content_rect,
       gfx::Size last_layer_bounds,
       gfx::Size current_layer_bounds,
       float last_layer_contents_scale,
       float current_layer_contents_scale,
       const gfx::Transform& last_screen_transform,
       const gfx::Transform& current_screen_transform,
       double current_frame_time_in_seconds,
       size_t max_tiles_for_interest_area);
 
   void DidBecomeActive();
   void DidBecomeRecycled();
 
   // For a given rect, iterates through tiles that can fill it.  If no
   // set of tiles with resources can fill the rect, then it will iterate
   // through null tiles with valid geometry_rect() until the rect is full.
   // If all tiles have resources, the union of all geometry_rects will
   // exactly fill rect with no overlap.
   class CC_EXPORT CoverageIterator {
    public:
     CoverageIterator(const PictureLayerTilingSet* set,
       float contents_scale,
-      gfx::Rect content_rect,
+      const gfx::Rect& content_rect,
       float ideal_contents_scale);
     ~CoverageIterator();
 
     // Visible rect (no borders), always in the space of rect,
     // regardless of the relative contents scale of the tiling.
     gfx::Rect geometry_rect() const;
     // Texture rect (in texels) for geometry_rect
     gfx::RectF texture_rect() const;
     // Texture size in texels
     gfx::Size texture_size() const;
@@ skipping 29 matching lines @@
   gfx::Size layer_bounds_;
   ScopedPtrVector<PictureLayerTiling> tilings_;
 
   friend class Iterator;
   DISALLOW_COPY_AND_ASSIGN(PictureLayerTilingSet);
 };
 
 }  // namespace cc
 
 #endif  // CC_RESOURCES_PICTURE_LAYER_TILING_SET_H_