Merge "Remove BackPanelController#staysHiddenBeforeSlopCrossed" into tm-qpr-dev am: 0f139ec6

Original change: https://googleplex-android-review.googlesource.com/c/platform/frameworks/base/+/21299080



Change-Id: Ifc7b549ed8b1b5c7f53798d39bd0a4fb4da83a10
Signed-off-by: Automerger Merge Worker <android-build-automerger-merge-worker@system.gserviceaccount.com>