mash: Migrate some system user files to common.

ash/system/tray/system_tray.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_SYSTEM_TRAY_H_
 #define ASH_SYSTEM_TRAY_SYSTEM_TRAY_H_
 
 #include <map>
 #include <memory>
 #include <vector>
 
 #include "ash/ash_export.h"
 #include "ash/common/system/tray/system_tray_bubble.h"
 #include "ash/common/system/tray/tray_background_view.h"
 #include "ash/system/cast/tray_cast.h"
-#include "ash/system/user/login_status.h"
 #include "base/macros.h"
 #include "base/memory/scoped_vector.h"
 #include "ui/views/bubble/tray_bubble_view.h"
 #include "ui/views/view.h"
 
 namespace ash {
+
+enum class LoginStatus;
 class ScreenTrayItem;
 class StatusAreaWidget;
 class SystemBubbleWrapper;
 class SystemTrayDelegate;
 class SystemTrayItem;
 class TrayAccessibility;
 class TrayDate;
 class TrayUpdate;
 class TrayUser;
 
@@ skipping 220 matching lines @@
   // A reference to the Screen share and capture item.
   ScreenTrayItem* screen_capture_tray_item_;  // not owned
   ScreenTrayItem* screen_share_tray_item_;  // not owned
 
   DISALLOW_COPY_AND_ASSIGN(SystemTray);
 };
 
 }  // namespace ash
 
 #endif  // ASH_SYSTEM_TRAY_SYSTEM_TRAY_H_