[Sync] Replace typedef with using.

components/sync/syncable/syncable_delete_journal.h

 // Copyright 2013 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_SYNCABLE_DELETE_JOURNAL_H_
 #define COMPONENTS_SYNC_SYNCABLE_SYNCABLE_DELETE_JOURNAL_H_
 
 #include <stddef.h>
 
 #include <map>
@@ skipping 13 matching lines @@
 class LessByID {
  public:
   inline bool operator()(const EntryKernel* a, const EntryKernel* b) const {
     return a->ref(ID) < b->ref(ID);
   }
 };
 // This should be |std::set<std::unique_ptr<EntryKernel>, LessByID>|. However,
 // DeleteJournal::TakeSnapshotAndClear needs to remove the unique_ptr from the
 // set, and std::set::extract is only available in C++17. TODO(avi): Switch to
 // using a std::set when Chromium allows C++17 use.
-typedef std::map<const EntryKernel*, std::unique_ptr<EntryKernel>, LessByID>
-    JournalIndex;
+using JournalIndex =
+    std::map<const EntryKernel*, std::unique_ptr<EntryKernel>, LessByID>;
 
 // DeleteJournal manages deleted entries that are not in sync directory until
 // it's safe to drop them after the deletion is confirmed with native models.
 // DeleteJournal is thread-safe and can be accessed on any thread. Has to hold
 // a valid transaction object when calling methods of DeleteJournal, thus each
 // method requires a non-null |trans| parameter.
 class DeleteJournal {
  public:
   // Initialize |delete_journals_| using |initial_journal|.
   explicit DeleteJournal(std::unique_ptr<JournalIndex> initial_journal);
@@ skipping 63 matching lines @@
   // saved to database.
   ModelTypeSet passive_delete_journal_types_;
 
   DISALLOW_COPY_AND_ASSIGN(DeleteJournal);
 };
 
 }  // namespace syncable
 }  // namespace syncer
 
 #endif  // COMPONENTS_SYNC_SYNCABLE_SYNCABLE_DELETE_JOURNAL_H_