Merge "Make PI created by AlertWindowNotification immutable" into rvc-dev am: de2933d5 am: 3a505ce3 am: 99b8a83a

Original change: https://googleplex-android-review.googlesource.com/c/platform/frameworks/base/+/11623674

Change-Id: I436a5b58c71fd7219b1c3f22a81a31be89a6dda8