GitLab

Remove the header in error and loading views and change the error view to look
more like a typical error page.

Bug: 907638
Change-Id: I6aca95c1bd6e1334b86416879283b0a26471719e
Reviewed-on: https://chromium-review.googlesource.com/c/1347215Reviewed-by: Theresa <twellington@chromium.org>
Commit-Queue: Cathy Li <chili@chromium.org>
Cr-Commit-Position: refs/heads/master@{#612074}