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

ui/views/controls/button/menu_button.cc

-// 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.
 
 #include "ui/views/controls/button/menu_button.h"
 
 #include "base/utf_string_conversions.h"
 #include "grit/ui_resources.h"
 #include "grit/ui_strings.h"
 #include "ui/base/accessibility/accessible_view_state.h"
 #include "ui/base/dragdrop/drag_drop_types.h"
@@ skipping 117 matching lines @@
     SetState(BS_NORMAL);
 
     // We must return false here so that the RootView does not get stuck
     // sending all mouse pressed events to us instead of the appropriate
     // target.
     return false;
   }
   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_) {
     gfx::Insets insets = GetInsets();
 
     // We can not use the views' mirroring infrastructure for mirroring a
     // MenuButton control (see TextButton::OnPaint() for a detailed explanation
     // regarding why we can not flip the canvas). Therefore, we need to
     // manually mirror the position of the down arrow.
     gfx::Rect arrow_bounds(width() - insets.right() -
@@ skipping 104 matching lines @@
   if (!GetWidget()) {
     NOTREACHED();
     return 0;
   }
 
   gfx::Rect monitor_bounds = GetWidget()->GetWorkAreaBoundsInScreen();
   return monitor_bounds.right() - 1;
 }
 
 }  // namespace views