[Sync] Replace typedef with using.

components/sync/engine_impl/syncer.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 COMPONENTS_SYNC_ENGINE_IMPL_SYNCER_H_
 #define COMPONENTS_SYNC_ENGINE_IMPL_SYNCER_H_
 
 #include <stdint.h>
 
 #include <vector>
@@ skipping 16 matching lines @@
 // cycles consist of downloading updates, parsing the response (aka. process
 // updates), applying updates while resolving conflicts, and committing local
 // changes.  Some of these steps may be skipped if they're deemed to be
 // unnecessary.
 //
 // A Syncer instance expects to run on a dedicated thread.  Calls to SyncShare()
 // may take an unbounded amount of time because it may block on network I/O, on
 // lock contention, or on tasks posted to other threads.
 class Syncer {
  public:
-  typedef std::vector<int64_t> UnsyncedMetaHandles;
+  using UnsyncedMetaHandles = std::vector<int64_t>;
 
   explicit Syncer(CancelationSignal* cancelation_signal);
   virtual ~Syncer();
 
   // Whether an early exist was requested due to a cancelation signal.
   bool ExitRequested();
 
   // Whether the syncer is in the middle of a sync cycle.
   bool IsSyncing() const;
 
@@ skipping 77 matching lines @@
 
   // Whether the syncer is in the middle of a sync attempt.
   bool is_syncing_;
 
   DISALLOW_COPY_AND_ASSIGN(Syncer);
 };
 
 }  // namespace syncer
 
 #endif  // COMPONENTS_SYNC_ENGINE_IMPL_SYNCER_H_