Merge "Apply root task for launch activity animation." into udc-dev am: 181bcdba am: e2cdba05

Original change: https://googleplex-android-review.googlesource.com/c/platform/frameworks/base/+/23109637



Change-Id: Ic2d3f68604f392e37c310483677e41934a3d30f9
Signed-off-by: Automerger Merge Worker <android-build-automerger-merge-worker@system.gserviceaccount.com>