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

ash/common/system/update/tray_update.h

 // Copyright (c) 2012 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.
 
 #ifndef ASH_COMMON_SYSTEM_UPDATE_TRAY_UPDATE_H_
 #define ASH_COMMON_SYSTEM_UPDATE_TRAY_UPDATE_H_
 
 #include "ash/ash_export.h"
 #include "ash/common/system/tray/tray_image_item.h"
 #include "ash/common/system/update/update_observer.h"
+#include "ash/public/interfaces/update.mojom.h"
 #include "base/macros.h"
 
 namespace views {
 class View;
 }
 
 namespace ash {
 
-// The system update tray item. Exported for test.
+// The system update tray item. The tray icon stays visible once an update
+// notification is received. The icon only disappears after a reboot to apply
+// the update. Exported for test.
 class ASH_EXPORT TrayUpdate : public TrayImageItem, public UpdateObserver {
  public:
   explicit TrayUpdate(SystemTray* system_tray);
   ~TrayUpdate() override;
 
  private:
+  class UpdateView;
+
   // Overridden from TrayImageItem.
   bool GetInitialVisibility() override;
   views::View* CreateDefaultView(LoginStatus status) override;
 
   // Overridden from UpdateObserver.
-  void OnUpdateRecommended(const UpdateInfo& info) override;
+  void ShowUpdateIcon(mojom::UpdateSeverity severity,
+                      bool factory_reset_required) override;
+
+  bool update_required_ = false;
+  mojom::UpdateSeverity severity_ = mojom::UpdateSeverity::NONE;
+  bool factory_reset_required_ = false;
 
   DISALLOW_COPY_AND_ASSIGN(TrayUpdate);
 };
 
 }  // namespace ash
 
 #endif  // ASH_COMMON_SYSTEM_UPDATE_TRAY_UPDATE_H_