Rounded corners on app transitions

Test: Manualy launch an app
Test: Press home when activity is on top of the stack
Test: Quick scrub
Test: Swipe up on the home button, swipe down
Bug: 111514493
Fixes: 116745318
Change-Id: I66d25bc433061ede46107ea9651c198614306692
(cherry picked from commit faa44330)