Merge "Adding support for extending back behavior in Launcher" into tm-dev am:...

Merge "Adding support for extending back behavior in Launcher" into tm-dev am: a2929870 am: d023ac2b am: fb0c85c8

Original change: https://googleplex-android-review.googlesource.com/c/platform/packages/apps/Launcher3/+/18187213



Change-Id: Ib1891f1d90ea7c3fca3cf53fab13fc70279bd70e
Signed-off-by: Automerger Merge Worker <android-build-automerger-merge-worker@system.gserviceaccount.com>