Remove #pragma once from sync

sync/internal_api/public/util/syncer_error.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_INTERNAL_API_PUBLIC_UTIL_SYNCER_ERROR_H_
 #define SYNC_INTERNAL_API_PUBLIC_UTIL_SYNCER_ERROR_H_
-#pragma once
 
 namespace syncer {
 
 // This enum describes all the ways a SyncerCommand can fail.
 //
 // SyncerCommands do many different things, but they share a common function
 // signature.  This enum, the return value for all SyncerCommands, must be able
 // to describe any possible failure for all SyncerComand.
 //
 // For convenience, functions which are invoked only by SyncerCommands may also
@@ skipping 19 matching lines @@
   SERVER_RESPONSE_VALIDATION_FAILED,
 
   SYNCER_OK
 };
 
 const char * GetSyncerErrorString(SyncerError);
 
 }  // namespace syncer
 
 #endif  // SYNC_INTERNAL_API_PUBLIC_UTIL_SYNCER_ERROR_H_