/lib/udev/rules.d/98-android-tools-adbd.rules is in android-tools-adbd 5.1.1r36+git20160322-0ubuntu3.
This file is owned by root:root, with mode 0o644.
The actual contents of the file can be viewed below.
1 | ACTION=="add", KERNEL=="android_adb", GROUP="phablet", MODE="0660"
|