services: fix gn check

gn check fails because the test case does not have the
necessary dependency.

Change-Id: I2cdfa762e910b54edc446e4abbfb7a718357610a
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/4998069
Reviewed-by: Scott Violet <sky@chromium.org>
Reviewed-by: Ken Rockot <rockot@google.com>
Reviewed-by: Emily Stark <estark@chromium.org>
Commit-Queue: Scott Violet <sky@chromium.org>
Cr-Commit-Position: refs/heads/main@{#1218779}