cc: Don't pass simple well-defined classes by reference.

cc/resources/tile.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_H_
 #define CC_RESOURCES_TILE_H_
 
 #include "base/memory/ref_counted.h"
 #include "base/memory/scoped_ptr.h"
 #include "base/memory/scoped_vector.h"
@@ skipping 36 matching lines @@
 
   scoped_ptr<base::Value> AsValue() const;
 
   const ManagedTileState::DrawingInfo& drawing_info() const {
     return managed_state_.drawing_info;
   }
   ManagedTileState::DrawingInfo& drawing_info() {
     return managed_state_.drawing_info;
   }
 
-  const gfx::Rect& opaque_rect() const { return opaque_rect_; }
+  gfx::Rect opaque_rect() const { return opaque_rect_; }
   bool has_text() const {
     return managed_state_.picture_pile_analysis.has_text;
   }
 
   float contents_scale() const { return contents_scale_; }
   gfx::Rect content_rect() const { return content_rect_; }
 
   int layer_id() const { return layer_id_; }
 
   void set_picture_pile(scoped_refptr<PicturePileImpl> pile) {
@@ skipping 27 matching lines @@
   TilePriority priority_[NUM_BIN_PRIORITIES];
   ManagedTileState managed_state_;
   int layer_id_;
 
   DISALLOW_COPY_AND_ASSIGN(Tile);
 };
 
 }  // namespace cc
 
 #endif  // CC_RESOURCES_TILE_H_