Merge "Prevent NPE when dragging last bubble from expanded state" into rvc-dev am: d4952538 am: bfca6d95

Original change: https://googleplex-android-review.googlesource.com/c/platform/frameworks/base/+/11832765

Change-Id: I7f8d03e6ec52c0c90d2495d4973db424353e7565