GitLab

This should help mmke it clear that you can't pass null
for keys_to_remove.

Change-Id: I63a86d6253cdd3b0e609942edf306ccd88b47a9c
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/2148058Reviewed-by: ssid <ssid@chromium.org>
Commit-Queue: Dan H <harringtond@chromium.org>
Cr-Commit-Position: refs/heads/master@{#761022}