@wang16, here is an async operation for notification icon image download, and ```RunUpdateNotificationIconOnUIThread``` will call ```UpdateNotificationIcon``` on the bridge which would finally call ```XWalkDefaultNotificationService::updateNotifcationIcon```, right?

One thing I am concerned is, does it mean that the notification is only showed after the notification icon is downloaded? The ```showNotification``` seems to be called twice in case of the icon is available, or it is by-design?