Merge "Fix stage stay empty if close transition request before task vanished"...

Merge "Fix stage stay empty if close transition request before task vanished" into udc-dev am: 445da648

Original change: https://googleplex-android-review.googlesource.com/c/platform/frameworks/base/+/22756019



Change-Id: I09b3b4e172fc7eff2f652e4dabb30a6a6f9f8244
Signed-off-by: Automerger Merge Worker <android-build-automerger-merge-worker@system.gserviceaccount.com>