mash: Move shelf menu code to //ash/common/shelf

ash/shelf/shelf_menu_model.h

-// Copyright 2013 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_SHELF_SHELF_MENU_MODEL_H_
-#define ASH_SHELF_SHELF_MENU_MODEL_H_
-
-#include "ash/ash_export.h"
-#include "base/macros.h"
-#include "ui/base/models/simple_menu_model.h"
-
-namespace ash {
-
-// A special menu model which keeps track of an "active" menu item.
-class ASH_EXPORT ShelfMenuModel : public ui::SimpleMenuModel {
- public:
-  explicit ShelfMenuModel(ui::SimpleMenuModel::Delegate* delegate)
-      : ui::SimpleMenuModel(delegate) {}
-
-  // Returns |true| when the given |command_id| is active and needs to be drawn
-  // in a special state.
-  virtual bool IsCommandActive(int command_id) const = 0;
-
- private:
-  DISALLOW_COPY_AND_ASSIGN(ShelfMenuModel);
-};
-
-}  // namespace ash
-
-#endif  // ASH_SHELF_SHELF_MENU_MODEL_H_