Now sending accessibility events and playing click noises:
- Home
- Back
- Notification icons (if you tap; tap-and-hold/scrub is
silent)
- the clock area
I also added touch slop to the main nav buttons (should have
been there all along).
Bug: 3422943
Change-Id: Ib5ee1d3a7c79e60e05377715092cde3f7678ddcf