base

Support for tapping on an immersive-mode priority notification.

When the user taps on an intruder alert (the priority
notification in immersive mode), the .contentIntent in the
Notification object will be sent, just as we handle tapping
on a normal Notification in the windowshade.

Change-Id: Ib6991837b0b2122fe138cddacf347fdbc426b99d