/lib/udev/rules.d/99-android.rules is in lxc-android-config 0.230+16.04.20160328-0ubuntu1.
This file is owned by root:root, with mode 0o644.
The actual contents of the file can be viewed below.
1 2 3 | # udisks2 hint for devices to be marked as system devices (consumed by ciborium)
# mmcblk0 so far has always been system.
ACTION=="add|change", KERNEL=="mmcblk0*", ENV{UDISKS_SYSTEM}="1"
|