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

ash/common/system/tray/system_tray_controller.cc

 // Copyright 2016 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 "ash/common/system/tray/system_tray_controller.h"
 
 #include "ash/common/system/tray/system_tray_notifier.h"
 #include "ash/common/wm_shell.h"
 
 namespace ash {
@@ skipping 110 matching lines @@
 
 void SystemTrayController::SetClient(mojom::SystemTrayClientPtr client) {
   system_tray_client_ = std::move(client);
 }
 
 void SystemTrayController::SetUse24HourClock(bool use_24_hour) {
   hour_clock_type_ = use_24_hour ? base::k24HourClock : base::k12HourClock;
   WmShell::Get()->system_tray_notifier()->NotifyDateFormatChanged();
 }
 
+void SystemTrayController::ShowUpdateIcon(mojom::UpdateSeverity severity,
+                                          bool factory_reset_required) {
+  WmShell::Get()->system_tray_notifier()->ShowUpdateIcon(
+      severity, factory_reset_required);
+}
+
 }  // namespace ash