[Sync] Replace typedef with using.

components/sync/syncable/write_transaction_info.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_SYNCABLE_WRITE_TRANSACTION_INFO_H_
 #define COMPONENTS_SYNC_SYNCABLE_WRITE_TRANSACTION_INFO_H_
 
 #include <stddef.h>
 #include <stdint.h>
 
@@ skipping 19 matching lines @@
   base::DictionaryValue* ToValue(size_t max_mutations_size) const;
 
   int64_t id;
   // If tracked_objects::Location becomes assignable, we can use that
   // instead.
   std::string location_string;
   WriterTag writer;
   ImmutableEntryKernelMutationMap mutations;
 };
 
-typedef Immutable<WriteTransactionInfo> ImmutableWriteTransactionInfo;
+using ImmutableWriteTransactionInfo = Immutable<WriteTransactionInfo>;
 
 }  // namespace syncable
 }  // namespace syncer
 
 #endif  // COMPONENTS_SYNC_SYNCABLE_WRITE_TRANSACTION_INFO_H_