Remove #pragma once from sync

sync/api/sync_error_factory.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_API_SYNC_ERROR_FACTORY_H_
 #define SYNC_API_SYNC_ERROR_FACTORY_H_
-#pragma once
 
 #include <string>
 
 #include "base/location.h"
 #include "sync/api/sync_error.h"
 
 namespace syncer {
 
 class SyncErrorFactory {
  public:
   SyncErrorFactory();
   virtual ~SyncErrorFactory();
 
   // Creates a SyncError object and uploads this call stack to breakpad.
   virtual SyncError CreateAndUploadError(
       const tracked_objects::Location& location,
       const std::string& message) = 0;
 };
 
 }  // namespace syncer
 
 #endif  // SYNC_API_SYNC_ERROR_FACTORY_H_