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

ui/views/controls/button/menu_button.cc

Index: ui/views/controls/button/menu_button.cc
diff --git a/ui/views/controls/button/menu_button.cc b/ui/views/controls/button/menu_button.cc
index 56ebbea60ac799eba515d5d560873e13cfadb263..faf6a9184f80843264f0f088541ccd5c3156370e 100644
--- a/ui/views/controls/button/menu_button.cc
+++ b/ui/views/controls/button/menu_button.cc
@@ -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.
 
@@ -136,7 +136,7 @@ bool MenuButton::Activate() {
   return true;
 }
 
-void MenuButton::PaintButton(gfx::Canvas* canvas, PaintButtonMode mode) {
+void MenuButton::PaintButton(gfx::CanvasSkia* canvas, PaintButtonMode mode) {
   TextButton::PaintButton(canvas, mode);
 
   if (show_menu_marker_) {