Protect GrantCredentialsPermissionActivity against overlay. am: f45dcfe1f5 am: 3f47c701f1 am: 765788de9a am: 3be814cbff am: 85e5d308e8

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

Change-Id: I053f991d201c271f498e37faea1bf204638bfe0b