ash: Use system tray mojo interface to show system update tray icon

ash/common/system/tray/system_tray_notifier.cc

Index: ash/common/system/tray/system_tray_notifier.cc
diff --git a/ash/common/system/tray/system_tray_notifier.cc b/ash/common/system/tray/system_tray_notifier.cc
index e530b8c43a4c3e484b8b9b2ca9d39beb8fd64639..6c1caec0d4582fb3206c9f539d7eed65f0a30f80 100644
--- a/ash/common/system/tray/system_tray_notifier.cc
+++ b/ash/common/system/tray/system_tray_notifier.cc
@@ -101,9 +101,10 @@ void SystemTrayNotifier::RemoveUpdateObserver(UpdateObserver* observer) {
   update_observers_.RemoveObserver(observer);
 }
 
-void SystemTrayNotifier::NotifyUpdateRecommended(const UpdateInfo& info) {
+void SystemTrayNotifier::ShowUpdateIcon(mojom::UpdateSeverity severity,
+                                        bool factory_reset_required) {
   for (auto& observer : update_observers_)
-    observer.OnUpdateRecommended(info);
+    observer.ShowUpdateIcon(severity, factory_reset_required);
 }
 
 void SystemTrayNotifier::AddUserObserver(UserObserver* observer) {