GitLab

This is necessary to be able to use async operation on handles.

This is a reland of https://codereview.chromium.org/552783004 after the
build dependency issue has been fixed.

R=sdefresne@chromium.org
BUG=415485

Review URL: https://codereview.chromium.org/577193002

Cr-Commit-Position: refs/heads/master@{#295451}