Enable user change background image in settings page in Aura build.

ash/desktop_background/desktop_background_view.h

 // Copyright (c) 2011 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 ASH_DESKTOP_BACKGROUND_DESKTOP_BACKGROUND_VIEW_H_
 #define ASH_DESKTOP_BACKGROUND_DESKTOP_BACKGROUND_VIEW_H_
 #pragma once
 
 #include "third_party/skia/include/core/SkBitmap.h"
 #include "ui/views/view.h"
 #include "ui/views/widget/widget_delegate.h"
 
 namespace ash {
 namespace internal {
 
 class DesktopBackgroundView : public views::WidgetDelegateView {
  public:
-  DesktopBackgroundView();
+  DesktopBackgroundView(const SkBitmap& wallpaper);
   virtual ~DesktopBackgroundView();
+  void SetWallpaper(const SkBitmap& wallpaper);

[flackr, 2012/03/07 20:50:28]

This currently isn't used anymore, right?

[bshe, 2012/03/07 23:48:35]

I still use it for changing the wallpaper. It seems if I remove the previous one
and use the constructor to change the wallpaper. The background stop paint. This
is essentially the same bug why toggle color mode does not work. After switch
back to image mode, the background somehow also stop paint and give an illusion
that switch to image mode failed. I guess once the bug got fixed, I can remove
the function. So I should probably add a todo here. What do you think?

[flackr, 2012/03/08 01:19:58]

Sounds good to me.

 
  private:
   // Overridden from views::View:
   virtual void OnPaint(gfx::Canvas* canvas) OVERRIDE;
   virtual bool OnMousePressed(const views::MouseEvent& event) OVERRIDE;
   virtual void OnMouseReleased(const views::MouseEvent& event) OVERRIDE;
 
   SkBitmap wallpaper_;
 
   DISALLOW_COPY_AND_ASSIGN(DesktopBackgroundView);
 };
 
 }  // namespace internal
 }  // namespace ash
 
 #endif  // ASH_DESKTOP_BACKGROUND_DESKTOP_BACKGROUND_VIEW_H_