[automerger skipped] Properly constrain FAB to its normal bounds when tucking am: 1840cab08d -s ours

am skip reason: Merged-In I5b28214677ae4822d1bbf95d624a8e71a1677149 with SHA-1 195158b104 is already in history

Original change: https://googleplex-android-review.googlesource.com/c/platform/frameworks/base/+/28017542

Change-Id: I9e789cabeae0d9df40775c23c145ec29fef2b3a1
Signed-off-by: Automerger Merge Worker <android-build-automerger-merge-worker@system.gserviceaccount.com>