GitLab

This was mostly done in https://codereview.chromium.org/668663006/, but:
* it missed things deriving from testing::Test for some reason;
* it didn't touch Windows-only files (for more obvious reasons).

R=sky@chromium.org
BUG=417463

Review URL: https://codereview.chromium.org/670743002

Cr-Commit-Position: refs/heads/master@{#300502}