GitLab

Part of extensions refactoring in https://codereview.chromium.org/562273006/

Landing manually because the tryjob patch step cannot handle empty binary files

BUG=none
TEST=none
TBR=yoz@chromium.org

Review URL: https://codereview.chromium.org/580283003

Cr-Commit-Position: refs/heads/master@{#295556}