Merge "Fix user switcher flicker." into udc-qpr-dev am: 3cb96b87 am: 5ac2acc2

Original change: https://googleplex-android-review.googlesource.com/c/platform/frameworks/base/+/24153952



Change-Id: I53e9b39311a9003e21f234ac94bb754436acc0cb
Signed-off-by: Automerger Merge Worker <android-build-automerger-merge-worker@system.gserviceaccount.com>