Returned from the ringtone picker as a Android.Net.Uri.
It will be one of: the picked ringtone, a Android.Net.Uri that equals NoType:android/provider/Settings$System;Href=../../../reference/android/provider/Settings.System.html#DEFAULT_RINGTONE_URI, NoType:android/provider/Settings$System;Href=../../../reference/android/provider/Settings.System.html#DEFAULT_NOTIFICATION_URI, or NoType:android/provider/Settings$System;Href=../../../reference/android/provider/Settings.System.html#DEFAULT_ALARM_ALERT_URI if the default was chosen, null if the "Silent" item was picked.