GitLab

Add a chrome flag so users can enable the feature without using a
switch.

BUG=832876

Change-Id: I18b754c892e37e995561bd22b6e95545683ff03e
Reviewed-on: https://chromium-review.googlesource.com/1012930Reviewed-by: Sadrul Chowdhury <sadrul@chromium.org>
Commit-Queue: Alex Newcomer <newcomer@chromium.org>
Cr-Commit-Position: refs/heads/master@{#555731}