Merge "Updating SysUI state when back enabled/disabled state change" into rvc-dev am: d71e76fd7b am: 3961746e9d

Original change: https://googleplex-android-review.googlesource.com/c/platform/frameworks/base/+/11965840

Change-Id: I02a7be6ad78dffdde27204b4710792733706b22b