/lib/udev/rules.d/99-gce.rules is in gce-compute-image-packages 20180129+dfsg1-0ubuntu3.
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 | # Give syslog write access to the kernel logs
KERNEL=="console", GROUP="syslog", MODE="0620"
# Switch to using NOOP as the default scheduler per GCE request
SUBSYSTEM=="block", ACTION=="add|change", ENV{ID_VENDOR}=="*Google*", ATTR{queue/scheduler}="noop"
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