[Sync] Replace typedef with using.

components/sync/syncable/directory_backing_store.cc

 // 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.
 
 #include "components/sync/syncable/directory_backing_store.h"
 
 #include <stddef.h>
 
 #include <limits>
 #include <unordered_set>
@@ skipping 1628 matching lines @@
 }
 
 // This function checks to see if the given list of Metahandles has any nodes
 // whose PARENT_ID values refer to ID values that do not actually exist.
 // This function also checks that a root node with the correct id exists in the
 // set.
 // Returns true on success.
 bool DirectoryBackingStore::VerifyReferenceIntegrity(
     const Directory::MetahandlesMap* handles_map) {
   TRACE_EVENT0("sync", "SyncDatabaseIntegrityCheck");
-  typedef std::unordered_set<std::string> IdsSet;
+  using IdsSet = std::unordered_set<std::string>;
 
   IdsSet ids_set;
   bool is_ok = true;
 
   for (auto it = handles_map->begin(); it != handles_map->end(); ++it) {
     EntryKernel* entry = it->second.get();
     bool is_duplicate_id = !(ids_set.insert(entry->ref(ID).value()).second);
     is_ok = is_ok && !is_duplicate_id;
   }
 
@@ skipping 106 matching lines @@
   DCHECK(CalledOnValidThread());
   DCHECK(!catastrophic_error_handler.is_null());
   catastrophic_error_handler_ = catastrophic_error_handler;
   sql::Connection::ErrorCallback error_callback =
       base::Bind(&OnSqliteError, catastrophic_error_handler_);
   db_->set_error_callback(error_callback);
 }
 
 }  // namespace syncable
 }  // namespace syncer