GitLab

Forward declare instead. Also fix nits along the way.

Change-Id: I746a551d1ba7ac4eb85034a96464a8aaf600d6ec
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/1714667Reviewed-by: Takumi Fujimoto <takumif@chromium.org>
Commit-Queue: Lei Zhang <thestig@chromium.org>
Cr-Commit-Position: refs/heads/master@{#680055}