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

ui/views/widget/widget.cc

 // 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/widget/widget.h"
 
 #include "base/logging.h"
 #include "base/message_loop.h"
 #include "base/utf_string_conversions.h"
 #include "ui/base/hit_test.h"
@@ skipping 1010 matching lines @@
         // It doesn't, and so a clear is required.
         force_clear = true;
       }
     }
   }
 
   compositor->Draw(force_clear);
   return true;
 }
 
-void Widget::OnNativeWidgetPaint(gfx::Canvas* canvas) {
+void Widget::OnNativeWidgetPaint(gfx::CanvasSkia* canvas) {
   GetRootView()->Paint(canvas);
 }
 
 int Widget::GetNonClientComponent(const gfx::Point& point) {
   return non_client_view_ ?
       non_client_view_->NonClientHitTest(point) :
       HTNOWHERE;
 }
 
 bool Widget::OnKeyEvent(const KeyEvent& event) {
@@ skipping 241 matching lines @@
 
 ////////////////////////////////////////////////////////////////////////////////
 // internal::NativeWidgetPrivate, NativeWidget implementation:
 
 internal::NativeWidgetPrivate* NativeWidgetPrivate::AsNativeWidgetPrivate() {
   return this;
 }
 
 }  // namespace internal
 }  // namespace views