GitLab

Metrics logged from the CaptivePortalMetricsTabHelper are useful to
determine the users affected by a broken connection due to a Captive
Portal. However, it is not necessary to log these metrics continuously.
Keeping the tab helper behind a flag allows re-enabling the metrics in
the future in order to examine the issues caused by Captive Portals.

Cq-Include-Trybots: master.tryserver.chromium.mac:ios-simulator-cronet;master.tryserver.chromium.mac:ios-simulator-full-configs
Change-Id: I8c4fca02d85701ca1ef1b7bf0aec87cf08015bd0
Reviewed-on: https://chromium-review.googlesource.com/924571
Commit-Queue: Mike Dougherty <michaeldo@chromium.org>
Reviewed-by: Eugene But <eugenebut@chromium.org>
Cr-Commit-Position: refs/heads/master@{#537845}