- When the user drags down in the empty (not on a notification), we
scale up the clock in the interaction.
- If there are no notifications at all, we stay in KEYGUARD and let
the clock spring back.
- Rubberbanding is different for the case when there are no
notifications or only low-priority notifications, to indicate what
the user can expect when they lift his finger.
Bug: 16216907
Change-Id: I69d6552c96ef9e3d0d0b526bbd232d68bef47960
48bc36af05