mash: Move //ash/system/date to //ash/common

ash/common/system/chromeos/shutdown_policy_observer.h

 // Copyright 2014 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_SHUTDOWN_POLICY_OBSERVER_H_
-#define ASH_SYSTEM_CHROMEOS_SHUTDOWN_POLICY_OBSERVER_H_
+#ifndef ASH_COMMON_SYSTEM_CHROMEOS_SHUTDOWN_POLICY_OBSERVER_H_
+#define ASH_COMMON_SYSTEM_CHROMEOS_SHUTDOWN_POLICY_OBSERVER_H_
+
+#include "ash/ash_export.h"
 
 namespace ash {
 
 // Registered with SystemTrayDelegate to observe the |kRebootOnShutdown| policy.
 class ASH_EXPORT ShutdownPolicyObserver {
  public:
   // Called when the value of the |kRebootOnShutdown| policy is changed.
   virtual void OnShutdownPolicyChanged(bool reboot_on_shutdown) = 0;
 
  protected:
   virtual ~ShutdownPolicyObserver() {}
 };
 
 }  // namespace ash
 
-#endif  // ASH_SYSTEM_CHROMEOS_SHUTDOWN_POLICY_OBSERVER_H_
+#endif  // ASH_COMMON_SYSTEM_CHROMEOS_SHUTDOWN_POLICY_OBSERVER_H_