[Sync] Replace typedef with using.

components/sync/engine_impl/sync_scheduler_impl.h

 // Copyright 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_SYNC_SCHEDULER_IMPL_H_
 #define COMPONENTS_SYNC_ENGINE_IMPL_SYNC_SCHEDULER_IMPL_H_
 
 #include <map>
 #include <memory>
 #include <string>
@@ skipping 248 matching lines @@
   NudgeTracker nudge_tracker_;
 
   // Invoked to run through the sync cycle.
   std::unique_ptr<Syncer> syncer_;
 
   SyncCycleContext* cycle_context_;
 
   // A map tracking LOCAL NudgeSource invocations of ScheduleNudge* APIs,
   // organized by datatype. Each datatype that was part of the types requested
   // in the call will have its TimeTicks value updated.
-  typedef std::map<ModelType, base::TimeTicks> ModelTypeTimeMap;
+  using ModelTypeTimeMap = std::map<ModelType, base::TimeTicks>;
   ModelTypeTimeMap last_local_nudges_by_model_type_;
 
   // Used as an "anti-reentrancy defensive assertion".
   // While true, it is illegal for any new scheduling activity to take place.
   // Ensures that higher layers don't break this law in response to events that
   // take place during a sync cycle. We call this out because such violations
   // could result in tight sync loops hitting sync servers.
   bool no_scheduling_allowed_;
 
   // TryJob might get called for multiple reasons. It should only call
@@ skipping 20 matching lines @@
   // A second factory specially for weak_handle_this_, to allow the handle
   // to be const and alleviate threading concerns.
   base::WeakPtrFactory<SyncSchedulerImpl> weak_ptr_factory_for_weak_handle_;
 
   DISALLOW_COPY_AND_ASSIGN(SyncSchedulerImpl);
 };
 
 }  // namespace syncer
 
 #endif  // COMPONENTS_SYNC_ENGINE_IMPL_SYNC_SCHEDULER_IMPL_H_