GitLab

Remove the scrim's background color because the theme already dims the
background.

Bug: 989330, 989336
Change-Id: I488e171a4d70317df4a5a0de59e281e3e350fb3b
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/1744648
Commit-Queue: Sinan Sahin <sinansahin@google.com>
Reviewed-by: Theresa  <twellington@chromium.org>
Cr-Commit-Position: refs/heads/master@{#685354}