ash: Display system background while loading wallpaper.

ash/wm/workspace/system_background_controller.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 ASH_WM_WORKSPACE_SYSTEM_BACKGROUND_CONTROLLER_H_
 #define ASH_WM_WORKSPACE_SYSTEM_BACKGROUND_CONTROLLER_H_
 
 #include "ash/ash_export.h"
 #include "base/basictypes.h"
 
+typedef unsigned int SkColor;
+
 namespace aura {
 class RootWindow;
 };
 
 namespace ash {
 namespace internal {
 
 // SystemBackgroundController shows the system level background. See
 // kShellWindowId_SystemBackgroundContainer for a description of the system
 // level background.
 class ASH_EXPORT SystemBackgroundController {
  public:
-  explicit SystemBackgroundController(aura::RootWindow* root);
+  SystemBackgroundController(aura::RootWindow* root, SkColor color);
   ~SystemBackgroundController();
 
+  // Changes the background color.
+  void SetColor(SkColor color);
+
  private:
   class View;
 
   // View responsible for rendering the background. This is non-NULL if the
   // widget containing it is deleted. It is owned by the widget.
   View* view_;
 
   DISALLOW_COPY_AND_ASSIGN(SystemBackgroundController);
 };
 
 }  // namespace internal
 }  // namespace ash
 
 #endif  // ASH_WM_WORKSPACE_SYSTEM_BACKGROUND_CONTROLLER_H_