Handle private IPs in XFF directly from cache proxies

* It will favor private IPs over the squid/varnish IPs now.
* Also cleaned up some broken callers that were passing in an
  extra argument that was removed. Note sure how long that was
  broken, but it must have prevented the green highlighting.

bug: 48919
Change-Id: I9b6648abddc943679d81392dce473e5e97ce1dd3