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.h"
 #include "ash/common/system/tray/system_tray_notifier.h"
+#include "ash/common/system/update/tray_update.h"
+#include "ash/common/wm_root_window_controller.h"
 #include "ash/common/wm_shell.h"
+#include "ash/common/wm_window.h"
 
 namespace ash {
 
 SystemTrayController::SystemTrayController()
     : hour_clock_type_(base::GetHourClockType()) {}
 
 SystemTrayController::~SystemTrayController() {}
 
 void SystemTrayController::ShowSettings() {
   if (system_tray_client_)
@@ skipping 102 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) {
+  // Show the icon on all displays.
+  for (WmWindow* root : WmShell::Get()->GetAllRootWindows()) {
+    ash::SystemTray* tray = root->GetRootWindowController()->GetSystemTray();
+    // External monitors might not have a tray yet.
+    if (!tray)
+      continue;
+    tray->tray_update()->ShowUpdateIcon(severity, factory_reset_required);
+  }
+}
+
 }  // namespace ash