mash: Move SystemTrayImage and TrayImageItem to //ash/common

ash/system/chromeos/enterprise/tray_enterprise.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_CHROMEOS_ENTERPRISE_TRAY_ENTERPRISE_H
 #define ASH_SYSTEM_CHROMEOS_ENTERPRISE_TRAY_ENTERPRISE_H
 
+#include "ash/common/system/tray/system_tray_item.h"
 #include "ash/system/chromeos/enterprise/enterprise_domain_observer.h"
-#include "ash/system/tray/system_tray_item.h"
 #include "ash/system/tray/view_click_listener.h"
 #include "base/macros.h"
 
 namespace views {
 class View;
 }
 
 namespace ash {
 class LabelTrayView;
 class SystemTray;
@@ skipping 22 matching lines @@
  private:
   LabelTrayView* tray_view_;
 
   DISALLOW_COPY_AND_ASSIGN(TrayEnterprise);
 };
 
 } // namespace ash
 
 #endif  // ASH_SYSTEM_CHROMEOS_ENTERPRISE_TRAY_ENTERPRISE_H