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

webkit/renderer/compositor_bindings/scrollbar_impl.h

 // Copyright 2013 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 WEBKIT_RENDERER_COMPOSITOR_BINDINGS_SCROLLBAR_IMPL_H_
 #define WEBKIT_RENDERER_COMPOSITOR_BINDINGS_SCROLLBAR_IMPL_H_
 
 #include "base/basictypes.h"
 #include "base/memory/scoped_ptr.h"
 #include "cc/input/scrollbar.h"
@@ skipping 17 matching lines @@
   virtual cc::ScrollbarOrientation Orientation() const OVERRIDE;
   virtual bool IsLeftSideVerticalScrollbar() const OVERRIDE;
   virtual bool HasThumb() const OVERRIDE;
   virtual bool IsOverlay() const OVERRIDE;
   virtual gfx::Point Location() const OVERRIDE;
   virtual int ThumbThickness() const OVERRIDE;
   virtual int ThumbLength() const OVERRIDE;
   virtual gfx::Rect TrackRect() const OVERRIDE;
   virtual void PaintPart(SkCanvas* canvas,
                          cc::ScrollbarPart part,
-                         gfx::Rect content_rect) OVERRIDE;
+                         const gfx::Rect& content_rect) OVERRIDE;
 
  private:
   scoped_ptr<blink::WebScrollbar> scrollbar_;
   blink::WebScrollbarThemePainter painter_;
   scoped_ptr<blink::WebScrollbarThemeGeometry> geometry_;
 
   DISALLOW_COPY_AND_ASSIGN(ScrollbarImpl);
 };
 
 }  // namespace webkit
 
 #endif  // WEBKIT_RENDERER_COMPOSITOR_BINDINGS_SCROLLBAR_IMPL_H_