GitLab

Make this a required field for new main/bool policies.

Since the item field isn't always copied over from main policies,
also add a warning check that the policy descriptions describe the
various cases.

Add items to MediaRecommendationsEnabled and BlockThirdPartyCookies.

No-Presubmit: true
BUG: 1139306
Change-Id: I519202ed9eeb491b27f804f26fbe94ae8e501598
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/2507457
Commit-Queue: Chris Sharp <csharp@chromium.org>
Reviewed-by: Yann Dago <ydago@chromium.org>
Reviewed-by: Owen Min <zmin@chromium.org>
Reviewed-by: Pavol Marko <pmarko@chromium.org>
Reviewed-by: Julian Pastarmov <pastarmovj@chromium.org>
Cr-Commit-Position: refs/heads/master@{#824431}