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

Merge "Apply root task for launch activity animation." into udc-dev am: 181bcdba am: 2ff43a98 am: de898182

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



Change-Id: I8eac7267ced3edc89e34320bfed197ec6127e5b4
Signed-off-by: Automerger Merge Worker <android-build-automerger-merge-worker@system.gserviceaccount.com>