Remove #pragma once from sync

sync/notifier/mock_sync_notifier_observer.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 SYNC_NOTIFIER_MOCK_SYNC_NOTIFIER_OBSERVER_H_
 #define SYNC_NOTIFIER_MOCK_SYNC_NOTIFIER_OBSERVER_H_
-#pragma once
 
 #include <string>
 
 #include "sync/notifier/sync_notifier_observer.h"
 #include "testing/gmock/include/gmock/gmock.h"
 
 namespace syncer {
 
 class MockSyncNotifierObserver : public SyncNotifierObserver {
  public:
   MockSyncNotifierObserver();
   virtual ~MockSyncNotifierObserver();
 
   MOCK_METHOD0(OnNotificationsEnabled, void());
   MOCK_METHOD1(OnNotificationsDisabled, void(NotificationsDisabledReason));
   MOCK_METHOD2(OnIncomingNotification,
                void(const syncer::ModelTypePayloadMap&,
                     IncomingNotificationSource));
 };
 
 }  // namespace syncer
 
 #endif  // SYNC_NOTIFIER_MOCK_SYNC_NOTIFIER_OBSERVER_H_