ui: Use skia::RefPtr<T> for implicit safe reference counting.

ui/gfx/canvas.h

 // 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.
 
 #ifndef UI_GFX_CANVAS_H_
 #define UI_GFX_CANVAS_H_
 
 #include <vector>
 
 #include "base/basictypes.h"
 #include "base/memory/scoped_ptr.h"
 #include "base/string16.h"
 #include "skia/ext/platform_canvas.h"
+#include "skia/ext/refptr.h"
 #include "ui/gfx/image/image_skia.h"
 #include "ui/gfx/native_widget_types.h"
 #include "ui/gfx/shadow_value.h"
 
 class SkBitmap;
 
 namespace gfx {
 
 class Rect;
 class Font;
@@ skipping 367 matching lines @@
   const gfx::ImageSkiaRep& GetImageRepToPaint(
       const gfx::ImageSkia& image,
       float user_defined_scale_factor_x,
       float user_defined_scale_factor_y)  const;
 
   // The device scale factor at which drawing on this canvas occurs.
   // An additional scale can be applied via Canvas::Scale(). However,
   // Canvas::Scale() does not affect |scale_factor_|.
   ui::ScaleFactor scale_factor_;
 
-  scoped_ptr<skia::PlatformCanvas> owned_canvas_;
+  skia::RefPtr<skia::PlatformCanvas> owned_canvas_;
   SkCanvas* canvas_;
 
   DISALLOW_COPY_AND_ASSIGN(Canvas);
 };
 
 }  // namespace gfx
 
 #endif  // UI_GFX_CANVAS_H_