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

ash/system/tray/default_system_tray_delegate.cc

Index: ash/system/tray/default_system_tray_delegate.cc
diff --git a/ash/system/tray/default_system_tray_delegate.cc b/ash/system/tray/default_system_tray_delegate.cc
index fda48075ec2a16db115abc50ec9a13f781bd3346..b86b562f92af8c95f862bc4f40c535dded8d2705 100644
--- a/ash/system/tray/default_system_tray_delegate.cc
+++ b/ash/system/tray/default_system_tray_delegate.cc
@@ -90,8 +90,11 @@ bool DefaultSystemTrayDelegate::IsUserSupervised() const {
   return false;
 }
 
-bool DefaultSystemTrayDelegate::SystemShouldUpgrade() const {
-  return true;
+void DefaultSystemTrayDelegate::GetSystemUpdateInfo(UpdateInfo* info) const {
+  DCHECK(info);
+  info->severity = UpdateInfo::UPDATE_NORMAL;
+  info->update_required = true;
+  info->factory_reset_required = false;
 }
 
 base::HourClockType DefaultSystemTrayDelegate::GetHourClockType() const {