[automerger skipped] Mark GrantPermissions callback as nullable am: 431b9727 -s ours

am skip reason: Merged-In I7fa6f428512cf94518585b2fd5a4e0d9685923d7 with SHA-1 196cec2e is already in history

Original change: https://googleplex-android-review.googlesource.com/c/platform/packages/modules/Permission/+/26214514



Change-Id: Id3466b37a0937fb8558d7db5b20314fddade4137
Signed-off-by: Automerger Merge Worker <android-build-automerger-merge-worker@system.gserviceaccount.com>