GitLab

Progress center groups are not used, remove the code.

Move ProgressCenterItem array to progress_center_panel.js to replace
the equivalent from progress_center_item_group.js

Bug: 1027012
Change-Id: I7e9584aa8992ca0ece616bc7a046fb2da50f69a2
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/2568919
Commit-Queue: Alex Danilo <adanilo@chromium.org>
Reviewed-by: Luciano Pacheco <lucmult@chromium.org>
Cr-Commit-Position: refs/heads/master@{#832712}