Update the update_reference_builds script.

The chrome-archive bucket is no longer updated and so we're pulling
from chrome-unsigned instead.

This patch also removes code for pulling from anywhere other than
official builds.

BUG=405792

Review URL: https://codereview.chromium.org/502593002

Cr-Commit-Position: refs/heads/master@{#291560}
git-svn-id: svn://svn.chromium.org/chrome/trunk/src@291560 0039d316-1c4b-4281-b951-d872f2087c98
1 file changed