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

cc/test/fake_scrollbar.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_TEST_FAKE_SCROLLBAR_H_
 #define CC_TEST_FAKE_SCROLLBAR_H_
 
 #include "base/compiler_specific.h"
 #include "cc/input/scrollbar.h"
 #include "third_party/skia/include/core/SkColor.h"
@@ skipping 10 matching lines @@
   virtual ScrollbarOrientation Orientation() const OVERRIDE;
   virtual bool IsLeftSideVerticalScrollbar() const OVERRIDE;
   virtual gfx::Point Location() const OVERRIDE;
   virtual bool IsOverlay() const OVERRIDE;
   virtual bool HasThumb() const OVERRIDE;
   virtual int ThumbThickness() const OVERRIDE;
   virtual int ThumbLength() const OVERRIDE;
   virtual gfx::Rect TrackRect() const OVERRIDE;
   virtual void PaintPart(SkCanvas* canvas,
                          ScrollbarPart part,
-                         gfx::Rect content_rect) OVERRIDE;
+                         const gfx::Rect& content_rect) OVERRIDE;
 
   void set_location(gfx::Point location) { location_ = location; }
-  void set_track_rect(gfx::Rect track_rect) { track_rect_ = track_rect; }
+  void set_track_rect(const gfx::Rect& track_rect) { track_rect_ = track_rect; }
   void set_thumb_thickness(int thumb_thickness) {
       thumb_thickness_ = thumb_thickness;
   }
   void set_thumb_length(int thumb_length) { thumb_length_ = thumb_length; }
 
  private:
   bool paint_;
   bool has_thumb_;
   bool is_overlay_;
   int thumb_thickness_;
   int thumb_length_;
   gfx::Point location_;
   gfx::Rect track_rect_;
   SkColor fill_color_;
 
   DISALLOW_COPY_AND_ASSIGN(FakeScrollbar);
 };
 
 }  // namespace cc
 
 #endif  // CC_TEST_FAKE_SCROLLBAR_H_