mash: Move SystemTrayImage and TrayImageItem to //ash/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/system/tray/system_tray_item.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);
@@ skipping 15 matching lines @@
 
   // True if the separator gets shown.
   bool separator_shown_;
 
   DISALLOW_COPY_AND_ASSIGN(TrayUserSeparator);
 };
 
 }  // namespace ash
 
 #endif  // ASH_SYSTEM_USER_TRAY_USER_SEPARATOR_H_