Move app list from ash to ui.

ash/app_list/app_list_item_model_observer.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_APP_LIST_APP_LIST_ITEM_MODEL_OBSERVER_H_
-#define ASH_APP_LIST_APP_LIST_ITEM_MODEL_OBSERVER_H_
-#pragma once
-
-#include "ash/ash_export.h"
-
-namespace ash {
-
-class ASH_EXPORT AppListItemModelObserver {
- public:
-  // Invoked after item's icon is changed.
-  virtual void ItemIconChanged() = 0;
-
-  // Invoked after item's title is changed.
-  virtual void ItemTitleChanged() = 0;
-
-  // Invoked after item's highlighted state is changed.
-  virtual void ItemHighlightedChanged() = 0;
-
- protected:
-  virtual ~AppListItemModelObserver() {}
-};
-
-}  // namespace ash
-
-#endif  // ASH_APP_LIST_APP_LIST_ITEM_MODEL_OBSERVER_H_