- Add edge menu bg assets.

NOTRY=true
BUG=400549
R=aurimas@chromium.org

Review URL: https://codereview.chromium.org/463203003

Cr-Commit-Position: refs/heads/master@{#289413}
git-svn-id: svn://svn.chromium.org/chrome/trunk/src@289413 0039d316-1c4b-4281-b951-d872f2087c98