GitLab

This flag will be used as a killswitch for the default browser
fullscreen promo UI.

Bug: 1107489
Change-Id: I47159e1a1e1d4a8466b598d4d8236b41e942c6c6
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/2405892
Commit-Queue: Chris Lu <thegreenfrog@chromium.org>
Reviewed-by: Rohit Rao <rohitrao@chromium.org>
Cr-Commit-Position: refs/heads/master@{#806359}