Merge "Allow delete empty TaskFragment in PiP" into tm-dev am: d41df35243

Original change: https://googleplex-android-review.googlesource.com/c/platform/frameworks/base/+/17800404

Change-Id: I699a8444ea9a29cd155889193bd66aba1b8e46ef
Signed-off-by: Automerger Merge Worker <android-build-automerger-merge-worker@system.gserviceaccount.com>