GitLab

Add an API for getting the feed items for a feed
when we want to display them and also feed items
for continue watching.

BUG=1053599

Change-Id: Id40e56035adb5fea25176f4ee9ed983d54c2f1da
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/2227885
Commit-Queue: Becca Hughes <beccahughes@chromium.org>
Reviewed-by: Tom Sepez <tsepez@chromium.org>
Reviewed-by: Tommy Steimel <steimel@chromium.org>
Cr-Commit-Position: refs/heads/master@{#776283}