Merge "Changing TaskStackChangeListener to an interface" into tm-dev am: 3b952a4a am: dc6d5856

Original change: https://googleplex-android-review.googlesource.com/c/platform/frameworks/base/+/17724905



Change-Id: I6d7ceeff66245b54237ca8d8d019871fe944f2db
Signed-off-by: Automerger Merge Worker <android-build-automerger-merge-worker@system.gserviceaccount.com>