cc: Create a cc::ScrollbarThemePainter and an adapter class in compositor bindings.

cc/layer_painter.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_LAYER_PAINTER_H_
 #define CC_LAYER_PAINTER_H_
 
 #include "cc/cc_export.h"
 
 class SkCanvas;
 
 namespace gfx {
 class Rect;
 class RectF;
 }
 
 namespace cc {
 
 class CC_EXPORT LayerPainter {
 public:
     virtual ~LayerPainter() { }
-    virtual void paint(SkCanvas*, const gfx::Rect& contentRect, gfx::RectF& opaque) = 0;
+    virtual void paint(SkCanvas*, gfx::Rect contentRect, gfx::RectF& opaque) = 0;
 };
 
-} // namespace cc
+}  // namespace cc
+
 #endif  // CC_LAYER_PAINTER_H_