Remove #pragma once from sync

sync/util/time.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.
 //
 // Time-related sync functions.
 
 #ifndef SYNC_UTIL_TIME_H_
 #define SYNC_UTIL_TIME_H_
-#pragma once
 
 #include <string>
 
 #include "base/basictypes.h"
 #include "base/time.h"
 
 namespace syncer {
 
 // Converts a time object to the format used in sync protobufs (ms
 // since the Unix epoch).
 int64 TimeToProtoTime(const base::Time& t);
 
 // Converts a time field from sync protobufs to a time object.
 base::Time ProtoTimeToTime(int64 proto_t);
 
 std::string GetTimeDebugString(const base::Time& t);
 
 }  // namespace syncer
 
 #endif  // SYNC_UTIL_TIME_H_