ui/gfx: Make gfx::Canvas inherit from gfx::CanvasSkia.

ui/views/controls/button/menu_button.h

Index: ui/views/controls/button/menu_button.h
diff --git a/ui/views/controls/button/menu_button.h b/ui/views/controls/button/menu_button.h
index 7f39e77076833daeb1d7f6fb96f43ccbf59471f8..d5f951a87e03f28567987d797cc2b02fe608a89c 100644
--- a/ui/views/controls/button/menu_button.h
+++ b/ui/views/controls/button/menu_button.h
@@ -1,4 +1,4 @@
-// Copyright (c) 2011 The Chromium Authors. All rights reserved.
+// Copyright (c) 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.
 
@@ -49,7 +49,8 @@ class VIEWS_EXPORT MenuButton : public TextButton {
   virtual bool Activate();
 
   // Overridden from TextButton for the potential use of a drop marker.
-  virtual void PaintButton(gfx::Canvas* canvas, PaintButtonMode mode) OVERRIDE;
+  virtual void PaintButton(gfx::CanvasSkia* canvas,
+                           PaintButtonMode mode) OVERRIDE;
 
   // Overridden from View:
   virtual gfx::Size GetPreferredSize() OVERRIDE;