mash: Move TrayUpdate to //ash/common

ash/system/tray_update.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_SYSTEM_TRAY_UPDATE_H_
-#define ASH_SYSTEM_TRAY_UPDATE_H_
-
-#include "ash/ash_export.h"
-#include "ash/common/system/tray/tray_image_item.h"
-#include "ash/common/system/update/update_observer.h"
-#include "base/macros.h"
-
-namespace views {
-class View;
-}
-
-namespace ash {
-
-// The system update tray item. Exported for test.
-class ASH_EXPORT TrayUpdate : public TrayImageItem, public UpdateObserver {
- public:
-  explicit TrayUpdate(SystemTray* system_tray);
-  ~TrayUpdate() override;
-
- private:
-  // Overridden from TrayImageItem.
-  bool GetInitialVisibility() override;
-  views::View* CreateDefaultView(LoginStatus status) override;
-
-  // Overridden from UpdateObserver.
-  void OnUpdateRecommended(const UpdateInfo& info) override;
-
-  DISALLOW_COPY_AND_ASSIGN(TrayUpdate);
-};
-
-}  // namespace ash
-
-#endif  // ASH_SYSTEM_TRAY_UPDATE_H_