Remove #pragma once from sync

sync/internal_api/change_reorder_buffer.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.
 //
 // Defines ChangeReorderBuffer, which can be used to sort a list of item
 // actions to achieve the ordering constraint required by the SyncObserver
 // interface of the SyncAPI.
 
 #ifndef SYNC_INTERNAL_API_CHANGE_REORDER_BUFFER_H_
 #define SYNC_INTERNAL_API_CHANGE_REORDER_BUFFER_H_
-#pragma once
 
 #include <map>
 #include <vector>
 
 #include "base/compiler_specific.h"
 #include "base/memory/linked_ptr.h"
 #include "sync/internal_api/public/base_transaction.h"
 #include "sync/internal_api/public/change_record.h"
 #include "sync/protocol/sync.pb.h"
 
@@ skipping 93 matching lines @@
 
   // Stores type-specific extra data per-ID.
   ExtraDataMap extra_data_;
 
   DISALLOW_COPY_AND_ASSIGN(ChangeReorderBuffer);
 };
 
 }  // namespace syncer
 
 #endif  // SYNC_INTERNAL_API_CHANGE_REORDER_BUFFER_H_