Merge "Prevent windows of embedding activities excluded from a11y" into sc-v2-dev am: 64f6df94e3 am: 52b2720e6d

Original change: https://googleplex-android-review.googlesource.com/c/platform/frameworks/base/+/15762966

Change-Id: I8c35c4741393c9d775dc3f5de7443ae7c783a253