When a FLAG_HIGH_PRIORITY notification is posted and the
foreground activity is immersive, this window will be shown
to the user. It disappears after a while (currently 10s,
which is far too long to be usable but is very handy for
testing) and can be dismissed by a tap.
Artwork is extremely rough; please ignore the aesthetics.
Still TODO:
- sticky alerts for ongoing priority notifications
- tap to launch PendingIntent associated with the
notification
Change-Id: Ief4a98b84cc836d33359bd7d65de9909f5186317
