Revert "chromeos: Move files in //ash/common to //ash, part 3"

ash/wallpaper/wallpaper_controller_observer.h

Index: ash/wallpaper/wallpaper_controller_observer.h
diff --git a/ash/wallpaper/wallpaper_controller_observer.h b/ash/wallpaper/wallpaper_controller_observer.h
deleted file mode 100644
index ed5476c3ef7ec3c4fb0404e61561a3726c4e31f7..0000000000000000000000000000000000000000
--- a/ash/wallpaper/wallpaper_controller_observer.h
+++ /dev/null
@@ -1,28 +0,0 @@
-// 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_WALLPAPER_WALLPAPER_CONTROLLER_OBSERVER_H_
-#define ASH_WALLPAPER_WALLPAPER_CONTROLLER_OBSERVER_H_
-
-#include "ash/ash_export.h"
-
-namespace ash {
-
-class ASH_EXPORT WallpaperControllerObserver {
- public:
-  // Invoked when the wallpaper data is changed.
-  virtual void OnWallpaperDataChanged() = 0;
-
-  // Invoked when the colors extracted from the current wallpaper change. May
-  // be called as a side effect of changing the wallpaper on the
-  // WallpaperController, e.g. WallpaperController::SetWallpaperImage().
-  virtual void OnWallpaperColorsChanged() {}
-
- protected:
-  virtual ~WallpaperControllerObserver() {}
-};
-
-}  // namespace ash
-
-#endif  // ASH_WALLPAPER_WALLPAPER_CONTROLLER_OBSERVER_H_