Protect GrantCredentialsPermissionActivity against overlay. am: f45dcfe1f5 am: 3f47c701f1 am: 765788de9a am: 364db883ad

Original change: https://googleplex-android-review.googlesource.com/c/platform/frameworks/base/+/13029378

Change-Id: I0e002fdc58070bdb780bd33b7aea90f95d58436b