Remove #pragma once from sync

sync/js/js_event_details.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_JS_JS_EVENT_DETAILS_H_
 #define SYNC_JS_JS_EVENT_DETAILS_H_
-#pragma once
 
 // See README.js for design comments.
 
 #include <string>
 
 #include "base/values.h"
 #include "sync/internal_api/public/util/immutable.h"
 
 namespace syncer {
 
@@ skipping 18 matching lines @@
  private:
   typedef Immutable<DictionaryValue, HasSwapMemFnByPtr<DictionaryValue> >
       ImmutableDictionaryValue;
 
   ImmutableDictionaryValue details_;
 };
 
 }  // namespace syncer
 
 #endif  // SYNC_JS_JS_EVENT_DETAILS_H_