mash: Migrate some system user files to common.

ash/system/user/tray_user_separator.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_USER_TRAY_USER_SEPARATOR_H_
-#define ASH_SYSTEM_USER_TRAY_USER_SEPARATOR_H_
-
-#include "ash/ash_export.h"
-#include "ash/common/system/tray/system_tray_item.h"
-#include "base/macros.h"
-
-namespace ash {
-
-// This tray item is showing an additional separator line between the logged in
-// users and the rest of the system tray menu. The separator will only be shown
-// when there are at least two users logged in.
-class ASH_EXPORT TrayUserSeparator : public SystemTrayItem {
- public:
-  explicit TrayUserSeparator(SystemTray* system_tray);
-  ~TrayUserSeparator() override {}
-
-  // Returns true if the separator gets shown.
-  bool separator_shown() { return separator_shown_; }
-
- private:
-  // Overridden from SystemTrayItem.
-  views::View* CreateTrayView(LoginStatus status) override;
-  views::View* CreateDefaultView(LoginStatus status) override;
-  views::View* CreateDetailedView(LoginStatus status) override;
-  void DestroyTrayView() override {}
-  void DestroyDefaultView() override;
-  void DestroyDetailedView() override {}
-  void UpdateAfterLoginStatusChange(LoginStatus status) override {}
-  void UpdateAfterShelfAlignmentChange(ShelfAlignment alignment) override {}
-
-  // True if the separator gets shown.
-  bool separator_shown_;
-
-  DISALLOW_COPY_AND_ASSIGN(TrayUserSeparator);
-};
-
-}  // namespace ash
-
-#endif  // ASH_SYSTEM_USER_TRAY_USER_SEPARATOR_H_