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

cc/layer_painter.h

Index: cc/layer_painter.h
diff --git a/cc/layer_painter.h b/cc/layer_painter.h
index b9dce8d05ec83413333f2afebb8adde25a312a4c..dcf69da5e1693c1f8700795dbc025b001b706d70 100644
--- a/cc/layer_painter.h
+++ b/cc/layer_painter.h
@@ -2,7 +2,6 @@
 // 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_
 
@@ -20,8 +19,9 @@ 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_