[Sync] Replace typedef with using.

components/sync/engine/net/network_time_update_callback.h

 // Copyright 2013 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 COMPONENTS_SYNC_ENGINE_NET_NETWORK_TIME_UPDATE_CALLBACK_H_
 #define COMPONENTS_SYNC_ENGINE_NET_NETWORK_TIME_UPDATE_CALLBACK_H_
 
 #include "base/callback.h"
 #include "base/time/time.h"
 
 namespace syncer {
 
 // TODO(pvalenzuela): Avoid duplication of this typedef by defining it in a
 // common location. This is duplicated here because its original definition in
 // NetworkTimeTracker cannot be depended on.
 //
 // Callback for updating the network time.
 // Params:
 // const base::Time& network_time - the new network time.
 // const base::TimeDelta& resolution - how precise the reading is.
 // const base::TimeDelta& latency - the http request's latency.
-typedef base::Callback<
-    void(const base::Time&, const base::TimeDelta&, const base::TimeDelta&)>
-    NetworkTimeUpdateCallback;
+using NetworkTimeUpdateCallback = base::Callback<
+    void(const base::Time&, const base::TimeDelta&, const base::TimeDelta&)>;
 
 }  // namespace syncer
 
 #endif  // COMPONENTS_SYNC_ENGINE_NET_NETWORK_TIME_UPDATE_CALLBACK_H_