Only block default display.

- Only look at tasks on default display
- Always launch blocking activity on default display

Bug: 125434235
Test: TODO
Change-Id: I15ed5d1f17170ecbe30a458c57dfc4093fb6c891
(cherry picked from commit 3506d612467c2a90a6933e92798f3703eefccfb6)
2 files changed