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

ui/views/controls/scrollbar/base_scroll_bar_thumb.h

Index: ui/views/controls/scrollbar/base_scroll_bar_thumb.h
diff --git a/ui/views/controls/scrollbar/base_scroll_bar_thumb.h b/ui/views/controls/scrollbar/base_scroll_bar_thumb.h
index c7daf935e43d48cdc75e27f0940ada9a47c4089d..2a3fff6300c507b0d193e46501b504457f16ebb1 100644
--- a/ui/views/controls/scrollbar/base_scroll_bar_thumb.h
+++ b/ui/views/controls/scrollbar/base_scroll_bar_thumb.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.
 
@@ -12,7 +12,7 @@
 #include "ui/views/view.h"
 
 namespace gfx {
-class Canvas;
+class CanvasSkia;
 }
 
 namespace views {
@@ -49,7 +49,7 @@ class VIEWS_EXPORT BaseScrollBarThumb : public View {
 
  protected:
   // View overrides:
-  virtual void OnPaint(gfx::Canvas* canvas) OVERRIDE = 0;
+  virtual void OnPaint(gfx::CanvasSkia* canvas) OVERRIDE = 0;
   virtual void OnMouseEntered(const MouseEvent& event) OVERRIDE;
   virtual void OnMouseExited(const MouseEvent& event) OVERRIDE;
   virtual bool OnMousePressed(const MouseEvent& event) OVERRIDE;