Merge "Fix task missing after dropped an app in PIP to enter stage split" into sc-v2-dev am: 338f6e29db am: 6e8d614413

Original change: https://googleplex-android-review.googlesource.com/c/platform/frameworks/base/+/15715796

Change-Id: I7238136b2469213adb8136d705519648a8d5a222