Remove #pragma once from sync

sync/test/null_directory_change_delegate.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_TEST_NULL_DIRECTORY_CHANGE_DELEGATE_H_
 #define SYNC_TEST_NULL_DIRECTORY_CHANGE_DELEGATE_H_
-#pragma once
 
 #include "base/compiler_specific.h"
 #include "sync/syncable/directory_change_delegate.h"
 
 namespace syncer {
 namespace syncable {
 
 // DirectoryChangeDelegate that does nothing in all delegate methods.
 class NullDirectoryChangeDelegate : public DirectoryChangeDelegate {
  public:
   virtual ~NullDirectoryChangeDelegate();
 
   virtual void HandleCalculateChangesChangeEventFromSyncApi(
       const ImmutableWriteTransactionInfo& write_transaction_info,
       BaseTransaction* trans) OVERRIDE;
   virtual void HandleCalculateChangesChangeEventFromSyncer(
       const ImmutableWriteTransactionInfo& write_transaction_info,
       BaseTransaction* trans) OVERRIDE;
   virtual ModelTypeSet HandleTransactionEndingChangeEvent(
       const ImmutableWriteTransactionInfo& write_transaction_info,
       BaseTransaction* trans) OVERRIDE;
   virtual void HandleTransactionCompleteChangeEvent(
       ModelTypeSet models_with_changes) OVERRIDE;
 };
 
 }  // namespace syncable
 }  // namespace syncer
 
 #endif  // SYNC_TEST_NULL_DIRECTORY_CHANGE_DELEGATE_H_