mash: Move system tray cast code into //ash/common

ash/system/chromeos/screen_security/screen_share_tray_item.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_SYSTEM_CHROMEOS_SCREEN_SHARE_SCREEN_SHARE_TRAY_ITEM_H_
-#define ASH_SYSTEM_CHROMEOS_SCREEN_SHARE_SCREEN_SHARE_TRAY_ITEM_H_
-
-#include "ash/common/system/chromeos/screen_security/screen_share_observer.h"
-#include "ash/system/chromeos/screen_security/screen_tray_item.h"
-#include "base/macros.h"
-
-namespace views {
-class View;
-}
-
-namespace ash {
-
-class ASH_EXPORT ScreenShareTrayItem : public ScreenTrayItem,
-                                       public ScreenShareObserver {
- public:
-  explicit ScreenShareTrayItem(SystemTray* system_tray);
-  ~ScreenShareTrayItem() override;
-
- private:
-  // Overridden from SystemTrayItem.
-  views::View* CreateTrayView(LoginStatus status) override;
-  views::View* CreateDefaultView(LoginStatus status) override;
-
-  // Overridden from ScreenTrayItem.
-  void CreateOrUpdateNotification() override;
-  std::string GetNotificationId() override;
-
-  // Overridden from ScreenShareObserver.
-  void OnScreenShareStart(const base::Closure& stop_callback,
-                          const base::string16& helper_name) override;
-  void OnScreenShareStop() override;
-
-  base::string16 helper_name_;
-
-  DISALLOW_COPY_AND_ASSIGN(ScreenShareTrayItem);
-};
-
-}  // namespace ash
-
-#endif  // ASH_SYSTEM_CHROMEOS_SCREEN_SHARE_SCREEN_SHARE_TRAY_ITEM_H_