[Sync] Replace typedef with using.

components/sync_sessions/favicon_cache.h

Index: components/sync_sessions/favicon_cache.h
diff --git a/components/sync_sessions/favicon_cache.h b/components/sync_sessions/favicon_cache.h
index e35611e557b4d67c092ea022534d7f71d257b4a1..979f6a80ab6febe7ed96792f5dc3e3cee50036a6 100644
--- a/components/sync_sessions/favicon_cache.h
+++ b/components/sync_sessions/favicon_cache.h
@@ -123,13 +123,13 @@ class FaviconCache : public syncer::SyncableService,
 
 
   // Map of favicon url to favicon image.
-  typedef std::map<GURL, linked_ptr<SyncedFaviconInfo> > FaviconMap;
-  typedef std::set<linked_ptr<SyncedFaviconInfo>,
-                   FaviconRecencyFunctor> RecencySet;
+  using FaviconMap = std::map<GURL, linked_ptr<SyncedFaviconInfo>>;
+  using RecencySet =
+      std::set<linked_ptr<SyncedFaviconInfo>, FaviconRecencyFunctor>;
   // Map of page url to task id (for favicon loading).
-  typedef std::map<GURL, base::CancelableTaskTracker::TaskId> PageTaskMap;
+  using PageTaskMap = std::map<GURL, base::CancelableTaskTracker::TaskId>;
   // Map of page url to favicon url.
-  typedef std::map<GURL, GURL> PageFaviconMap;
+  using PageFaviconMap = std::map<GURL, GURL>;
 
   // Helper method to perform OnReceivedSyncFavicon work without worrying about
   // whether caller holds a sync transaction.