/lib/udev/rules.d/64-xorg-xkb.rules is in xserver-xorg-core-lts-trusty 2:1.15.1-0ubuntu2~precise5.
This file is owned by root:root, with mode 0o644.
The actual contents of the file can be viewed below.
1 2 3 4 5 6 7 8 | ACTION!="add|change", GOTO="xorg_xkb_end"
SUBSYSTEM!="input", GOTO="xorg_xkb_end"
KERNEL!="event*", GOTO="xorg_xkb_end"
# import keyboard layout from /etc/default/keyboard
ENV{ID_INPUT_KEY}=="?*", IMPORT{file}="/etc/default/keyboard"
LABEL="xorg_xkb_end"
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