Added Aura notification that relaunch and powerwash is required in case of downgrade.

ash/system/tray/system_tray_notifier.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_SYSTEM_TRAY_SYSTEM_TRAY_NOTIFIER_H_
 #define ASH_SYSTEM_TRAY_SYSTEM_TRAY_NOTIFIER_H_
 
 #include <string>
 #include <vector>
 
@@ skipping 17 matching lines @@
 #include "ash/system/chromeos/screen_security/screen_share_observer.h"
 #include "ash/system/chromeos/session/last_window_closed_observer.h"
 #include "ash/system/chromeos/session/logout_button_observer.h"
 #include "ash/system/chromeos/session/session_length_limit_observer.h"
 #include "ash/system/tray/media_security/media_capture_observer.h"
 #include "base/time/time.h"
 #endif
 
 namespace ash {
 
+struct UpdateInfo;
+
 #if defined(OS_CHROMEOS)
 class NetworkStateNotifier;
 #endif
 
 class ASH_EXPORT SystemTrayNotifier {
  public:
   SystemTrayNotifier();
   ~SystemTrayNotifier();
 
   void AddAccessibilityObserver(AccessibilityObserver* observer);
@@ skipping 66 matching lines @@
   void NotifyBluetoothDiscoveringChanged();
   void NotifyRefreshClock();
   void NotifyDateFormatChanged();
   void NotifySystemClockTimeUpdated();
   void NotifySystemClockCanSetTimeChanged(bool can_set_time);
   void NotifyRefreshIME();
   void NotifyLocaleChanged(LocaleObserver::Delegate* delegate,
                            const std::string& cur_locale,
                            const std::string& from_locale,
                            const std::string& to_locale);
-  void NotifyUpdateRecommended(UpdateObserver::UpdateSeverity severity);
+  void NotifyUpdateRecommended(const UpdateInfo& info);
   void NotifyUserUpdate();
   void NotifyUserAddedToSession();
 #if defined(OS_CHROMEOS)
   void NotifyShowLoginButtonChanged(bool show_login_button);
   void NotifyLogoutDialogDurationChanged(base::TimeDelta duration);
   void NotifySessionStartTimeChanged();
   void NotifySessionLengthLimitChanged();
   void NotifyRequestToggleWifi();
   void NotifyOnCaptivePortalDetected(const std::string& service_path);
   void NotifyEnterpriseDomainChanged();
@@ skipping 34 matching lines @@
   ObserverList<LastWindowClosedObserver> last_window_closed_observers_;
   scoped_ptr<NetworkStateNotifier> network_state_notifier_;
 #endif
 
   DISALLOW_COPY_AND_ASSIGN(SystemTrayNotifier);
 };
 
 }  // namespace ash
 
 #endif  // ASH_SYSTEM_TRAY_SYSTEM_TRAY_NOTIFIER_H_