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: If96e9c2ac74a5671d464f3b5c8304bbc39f3350a
Signed-off-by: Automerger Merge Worker <android-build-automerger-merge-worker@system.gserviceaccount.com>