Remove #pragma once from sync

sync/util/extensions_activity_monitor.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_UTIL_EXTENSIONS_ACTIVITY_MONITOR_H_
 #define SYNC_UTIL_EXTENSIONS_ACTIVITY_MONITOR_H_
-#pragma once
 
 #include <map>
 #include <string>
 
 #include "base/basictypes.h"
 
 namespace syncer {
 
 // An interface to monitor usage of extensions APIs to send to sync
 // servers, with the ability to purge data once sync servers have
@@ skipping 26 matching lines @@
   // bookmark write counts for common Records.
   virtual void PutRecords(const Records& records) = 0;
 
  protected:
   virtual ~ExtensionsActivityMonitor();
 };
 
 }  // namespace syncer
 
 #endif  // SYNC_UTIL_EXTENSIONS_ACTIVITY_MONITOR_H_