Merge "Fix the root task of secondary split screen could be overwritten." into...

Merge "Fix the root task of secondary split screen could be overwritten." into rvc-dev am: 67a056a9

Original change: https://googleplex-android-review.googlesource.com/c/platform/frameworks/base/+/11716093

Change-Id: Iffd37b6438cfad62cccb5a0d71676b93f6d8b668