Merge "Prevent flickering between fullscreen and multi-window of main stage"...

Merge "Prevent flickering between fullscreen and multi-window of main stage" into sc-v2-dev am: 5917a9cc

Original change: https://googleplex-android-review.googlesource.com/c/platform/frameworks/base/+/15216393

Change-Id: Ic024f46f1f12cff14d9b64ae76db883968a8dba5