Merge "Clear preferred top focusable root task" into sc-dev am: ba19c63b am:...

Merge "Clear preferred top focusable root task" into sc-dev am: ba19c63b am: dfa430c1 am: 739aa04b

Original change: https://googleplex-android-review.googlesource.com/c/platform/frameworks/base/+/14514106

Change-Id: I4d7eaf9369a2d8140752fb30a58259545687a681