[automerge] Add leash check in PipTaskOrganizer#fadeExistingPip 2p: 4353053c87

Original change: https://googleplex-android-review.googlesource.com/c/platform/frameworks/base/+/16719697

Bug: 197319184
Change-Id: I08c012637e1e7c38c579bec2175d69e4cf4e63a6