[Sync] Remove unneeded 'using syncer::' lines and 'syncer::' scopings

sync/notifier/sync_notifier.h

Index: sync/notifier/sync_notifier.h
diff --git a/sync/notifier/sync_notifier.h b/sync/notifier/sync_notifier.h
index 24c59a018c4f8126ef6a7f0457cae941a6597a47..0c775f47277ce5a98085312f81a485d19655dadb 100644
--- a/sync/notifier/sync_notifier.h
+++ b/sync/notifier/sync_notifier.h
@@ -40,13 +40,13 @@ class SyncNotifier {
   virtual void UpdateCredentials(
       const std::string& email, const std::string& token) = 0;
 
-  virtual void UpdateEnabledTypes(syncer::ModelTypeSet enabled_types) = 0;
+  virtual void UpdateEnabledTypes(ModelTypeSet enabled_types) = 0;
 
   // This is here only to support the old p2p notification implementation,
   // which is still used by sync integration tests.
   // TODO(akalin): Remove this once we move the integration tests off p2p
   // notifications.
-  virtual void SendNotification(syncer::ModelTypeSet changed_types) = 0;
+  virtual void SendNotification(ModelTypeSet changed_types) = 0;
 };
 }  // namespace syncer