Merge "Finishing root activity if having other running activities" into...

Merge "Finishing root activity if having other running activities" into sc-v2-dev am: f1a38d12 am: c0944305

Original change: https://googleplex-android-review.googlesource.com/c/platform/frameworks/base/+/15358030

Change-Id: Idb08936f77b16e08a2f8919792f33d144ba8b6c8