Remove #pragma once from sync

sync/syncable/directory.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_SYNCABLE_DIRECTORY_H_
 #define SYNC_SYNCABLE_DIRECTORY_H_
-#pragma once
 
 #include <set>
 #include <string>
 #include <vector>
 
 #include "base/file_util.h"
 #include "base/gtest_prod_util.h"
 #include "sync/internal_api/public/util/report_unrecoverable_error_function.h"
 #include "sync/internal_api/public/util/weak_handle.h"
 #include "sync/syncable/dir_open_result.h"
@@ skipping 588 matching lines @@
       report_unrecoverable_error_function_;
   bool unrecoverable_error_set_;
 
   InvariantCheckLevel invariant_check_level_;
 };
 
 }  // namespace syncable
 }  // namespace syncer
 
 #endif // SYNC_SYNCABLE_DIRECTORY_H_