Merge "Merge "Don't allow background apps to change theme" into sc-dev am: d47e6d84d1" into sc-qpr1-dev am: df4bc3589e

Original change: https://googleplex-android-review.googlesource.com/c/platform/frameworks/base/+/16517186

Change-Id: I7dc5a52f84fb1a45d539390bfcf525618edf2fc2