GitLab

Specify the custom background image via a <link rel="preload"...>
tag that's inserted at the time the page is served.

Bug: 853042
Change-Id: Id24b1815c66b32f04b1811e55c54b5066cfc9873
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/1592122Reviewed-by: Dan Beam <dbeam@chromium.org>
Reviewed-by: Kristi Park <kristipark@chromium.org>
Commit-Queue: Kyle Milka <kmilka@chromium.org>
Cr-Commit-Position: refs/heads/master@{#657446}