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 am: 5ff7da29 am: abef7dd6 am: aec26498

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

Change-Id: I10917c6a9b6302c2d864dc52e0330973c204b78c