Merge "Completely remove pinned task when starting a new PiP" into tm-dev am: bfbf74ae

Original change: https://googleplex-android-review.googlesource.com/c/platform/frameworks/base/+/18175783



Change-Id: Ic431640b3cae305ebff2554a0c1beef05ca6ced2
Signed-off-by: Automerger Merge Worker <android-build-automerger-merge-worker@system.gserviceaccount.com>