mash: Move ash/common/wm/shelf to ash/common/shelf

ash/common/wm/shelf/wm_shelf_observer.h

-// Copyright 2016 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_COMMON_WM_SHELF_WM_SHELF_OBSERVER_H_
-#define ASH_COMMON_WM_SHELF_WM_SHELF_OBSERVER_H_
-
-#include "ash/ash_export.h"
-#include "ash/common/wm/background_animator.h"
-#include "ash/common/wm/shelf/wm_shelf_types.h"
-
-namespace ash {
-
-class WmWindow;
-
-namespace wm {
-
-// Used to observe changes to the shelf.
-class ASH_EXPORT WmShelfObserver {
- public:
-  virtual void OnBackgroundUpdated(ShelfBackgroundType background_type,
-                                   BackgroundAnimatorChangeType change_type) {}
-  virtual void WillChangeVisibilityState(ShelfVisibilityState new_state) {}
-  virtual void OnShelfIconPositionsChanged() {}
-
- protected:
-  virtual ~WmShelfObserver() {}
-};
-
-}  // namespace wm
-}  // namespace ash
-
-#endif  // ASH_COMMON_WM_SHELF_WM_SHELF_OBSERVER_H_