Block touches under scrimmed bouncer

Fixes: 131386038
Test: swipe to bouncer and back on LS
Test: tap on notification, hit back on LS
Test: tap on notification on locked shade, try to interact with QS
Test: tap on notification on locked shade, hit back
Change-Id: I4e7c92abd8af2bba1918b7f1680d2a4b7377be12
2 files changed