GitLab

SetCustomBackgroundURL is equivalent to calling
SetCustomBackgroundURLWithAttributions with empty attributions. Remove
the separate API and instead just pass in empty attributions when
SetCustomBackgroundURL is called.

Bug: 961908

Change-Id: I52389d85219fdd03008717979f142cffe5ff1e62
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/1607431Reviewed-by: Emily Stark <estark@chromium.org>
Reviewed-by: Gayane Petrosyan <gayane@chromium.org>
Commit-Queue: Kyle Milka <kmilka@chromium.org>
Cr-Commit-Position: refs/heads/master@{#661982}