If we redirect from an https to an http site, ensure that we don't

      leak referrer information.

BUG=29920
TEST=URLRequestTestHTTP.HTTPSToHTTPRedirectNoRefererTest


Review URL: http://codereview.chromium.org/486015

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@34751 0039d316-1c4b-4281-b951-d872f2087c98