Remove #pragma once from sync

sync/notifier/non_blocking_invalidation_notifier.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.
 //
 // An implementation of SyncNotifier that wraps InvalidationNotifier
 // on its own thread.
 
 #ifndef SYNC_NOTIFIER_NON_BLOCKING_INVALIDATION_NOTIFIER_H_
 #define SYNC_NOTIFIER_NON_BLOCKING_INVALIDATION_NOTIFIER_H_
-#pragma once
 
 #include <string>
 
 #include "base/basictypes.h"
 #include "base/compiler_specific.h"
 #include "base/memory/ref_counted.h"
 #include "base/memory/weak_ptr.h"
 #include "base/observer_list.h"
 #include "jingle/notifier/base/notifier_options.h"
 #include "sync/internal_api/public/util/weak_handle.h"
@@ skipping 56 matching lines @@
   scoped_refptr<Core> core_;
   scoped_refptr<base::SingleThreadTaskRunner> parent_task_runner_;
   scoped_refptr<base::SingleThreadTaskRunner> network_task_runner_;
 
   DISALLOW_COPY_AND_ASSIGN(NonBlockingInvalidationNotifier);
 };
 
 }  // namespace syncer
 
 #endif  // SYNC_NOTIFIER_NON_BLOCKING_INVALIDATION_NOTIFIER_H_