[automerger skipped] DO NOT MERGE Intercept back button on user switcher screen am: a287650f am: c7629942 -s ours

am skip reason: subject contains skip directive

Original change: https://googleplex-android-review.googlesource.com/c/platform/frameworks/base/+/13689637

MUST ONLY BE SUBMITTED BY AUTOMERGER

Change-Id: I4e545b9c2e58643df20c9efb1e5b006de7db751c