Merge "Notify of new top task changes when a top task is moved to the back"...

Merge "Notify of new top task changes when a top task is moved to the back" into tm-dev am: a5bd9061 am: 85ba9133 am: f742634b

Original change: https://googleplex-android-review.googlesource.com/c/platform/frameworks/base/+/18759417



Change-Id: Iba01f1b50ccf23fc57cba4e03ab660d6a1ad7448
Signed-off-by: Automerger Merge Worker <android-build-automerger-merge-worker@system.gserviceaccount.com>