RingtonePickerActivity:  Keep cursor open while visible.

If we clear the cursor before we are actually invisible we
may do so during or right before the exit animation
and see weird results (in this case a copy of the dialog
which contains no ringtones).

Bug: 26972412
Change-Id: I48b2f4ca5a677085c718f6c7866b3b6d1ca03689
1 file changed