[Sync] Replace typedef with using.

components/sync/syncable/change_reorder_buffer.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_SYNCABLE_CHANGE_REORDER_BUFFER_H_
 #define COMPONENTS_SYNC_SYNCABLE_CHANGE_REORDER_BUFFER_H_
 
 #include <stdint.h>
 
 #include <map>
@@ skipping 49 matching lines @@
   // Output a reordered list of changes to |changes| using the items
   // that were pushed into the reorder buffer. |sync_trans| is used to
   // determine the ordering.  Returns true if successful, or false if
   // an error was encountered.
   bool GetAllChangesInTreeOrder(const BaseTransaction* sync_trans,
                                 ImmutableChangeRecordList* changes)
       WARN_UNUSED_RESULT;
 
  private:
   class Traversal;
-  typedef std::map<int64_t, ChangeRecord::Action> OperationMap;
-  typedef std::map<int64_t, sync_pb::EntitySpecifics> SpecificsMap;
-  typedef std::map<int64_t, linked_ptr<ExtraPasswordChangeRecordData>>
-      ExtraDataMap;
+  using OperationMap = std::map<int64_t, ChangeRecord::Action>;
+  using SpecificsMap = std::map<int64_t, sync_pb::EntitySpecifics>;
+  using ExtraDataMap =
+      std::map<int64_t, linked_ptr<ExtraPasswordChangeRecordData>>;
 
   // Stores the items that have been pushed into the buffer, and the type of
   // operation that was associated with them.
   OperationMap operations_;
 
   // Stores entity-specific ChangeRecord data per-ID.
   SpecificsMap specifics_;
 
   // Stores type-specific extra data per-ID.
   ExtraDataMap extra_data_;
 
   DISALLOW_COPY_AND_ASSIGN(ChangeReorderBuffer);
 };
 
 }  // namespace syncer
 
 #endif  // COMPONENTS_SYNC_SYNCABLE_CHANGE_REORDER_BUFFER_H_