Merge "Visual indicator of transition to fullscreen" into udc-dev am: da26654d am: b275d6c9

Original change: https://googleplex-android-review.googlesource.com/c/platform/frameworks/base/+/22168335



Change-Id: I62fb758b29ed93263b125ff518896c283ddb9863
Signed-off-by: Automerger Merge Worker <android-build-automerger-merge-worker@system.gserviceaccount.com>