Reland - cros: Add CHECK for screen unlock problem

ash/desktop_background/desktop_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_DESKTOP_BACKGROUND_DESKTOP_BACKGROUND_CONTROLLER_H_
 #define ASH_DESKTOP_BACKGROUND_DESKTOP_BACKGROUND_CONTROLLER_H_
 
 #include "ash/ash_export.h"
 #include "ash/desktop_background/desktop_background_resources.h"
 #include "ash/wm/window_animations.h"
@@ skipping 102 matching lines @@
   // . If loading a real wallpaper, there are cases that these tests crash
   // because the required widget is not ready. This function synchronously
   // creates an empty widget for those tests to prevent crashes. An example test
   // is SystemGestureEventFilterTest.ThreeFingerSwipe.
   void CreateEmptyWallpaper();
 
   // Returns the appropriate wallpaper resolution for all root windows.
   WallpaperResolution GetAppropriateResolution();
 
   // Move all desktop widgets to locked container.
-  void MoveDesktopToLockedContainer();
+  // Returns true if the desktop moved.
+  bool MoveDesktopToLockedContainer();
 
   // Move all desktop widgets to unlocked container.
-  void MoveDesktopToUnlockedContainer();
+  // Returns true if the desktop moved.
+  bool MoveDesktopToUnlockedContainer();
 
   // WindowObserver implementation.
   virtual void OnWindowDestroying(aura::Window* window) OVERRIDE;
 
  private:
   // An operation to asynchronously loads wallpaper.
   class WallpaperOperation;
 
   struct WallpaperData;
 
@@ skipping 11 matching lines @@
                                        int container_id);
 
   // Creates and adds component for current mode (either Widget or Layer) to
   // |root_window|.
   void InstallComponent(aura::RootWindow* root_window);
 
   // Creates and adds component for current mode (either Widget or Layer) to
   // all root windows.
   void InstallComponentForAllWindows();
 
-  // Moves all descktop components from one container to other across all root
-  // windows.
-  void ReparentBackgroundWidgets(int src_container, int dst_container);
+  // Moves all desktop components from one container to other across all root
+  // windows. Returns true if a desktop moved.
+  bool ReparentBackgroundWidgets(int src_container, int dst_container);
 
   // Returns id for background container for unlocked and locked states.
   int GetBackgroundContainerId(bool locked);
 
   // Send notification that background animation finished.
   void NotifyAnimationFinished();
 
   // Can change at runtime.
   bool locked_;
 
   BackgroundMode desktop_background_mode_;
 
   SkColor background_color_;
 
   // The current wallpaper.
   scoped_ptr<WallpaperData> current_wallpaper_;
 
   scoped_refptr<WallpaperOperation> wallpaper_op_;
 
   base::WeakPtrFactory<DesktopBackgroundController> weak_ptr_factory_;
 
   DISALLOW_COPY_AND_ASSIGN(DesktopBackgroundController);
 };
 
 }  // namespace ash
 
 #endif  // ASH_DESKTOP_BACKGROUND_DESKTOP_BACKGROUND_CONTROLLER_H_