Merge "Notify organizer when the last activity in TaskFragment enter PiP" into tm-dev am: 88671a050f am: 38f42547e4

Original change: https://googleplex-android-review.googlesource.com/c/platform/frameworks/base/+/17713423

Change-Id: I3439bb17ed2f7438133f2bbf01036761a0c7bfaf
Signed-off-by: Automerger Merge Worker <android-build-automerger-merge-worker@system.gserviceaccount.com>