Remove #pragma once from sync

sync/test/fake_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_TEST_FAKE_EXTENSIONS_ACTIVITY_MONITOR_H_
 #define SYNC_TEST_FAKE_EXTENSIONS_ACTIVITY_MONITOR_H_
-#pragma once
 
 #include "base/compiler_specific.h"
 #include "base/threading/non_thread_safe.h"
 #include "sync/util/extensions_activity_monitor.h"
 
 namespace syncer {
 
 // Fake non-thread-safe implementation of ExtensionsActivityMonitor
 // suitable to be used in single-threaded sync tests.
 class FakeExtensionsActivityMonitor
     : public ExtensionsActivityMonitor,
       public base::NonThreadSafe {
  public:
   FakeExtensionsActivityMonitor();
   virtual ~FakeExtensionsActivityMonitor();
 
   // ExtensionsActivityMonitor implementation.
   virtual void GetAndClearRecords(Records* buffer) OVERRIDE;
   virtual void PutRecords(const Records& records) OVERRIDE;
 
  private:
   Records records_;
 };
 
 }  // namespace syncer
 
 #endif  // SYNC_TEST_FAKE_EXTENSIONS_ACTIVITY_MONITOR_H_