net: don't assume that we have an SSLHostInfo.

sync doesn't run an HttpCache and therefore sync's requests don't pickup
an SSLHostInfo.

BUG=69522
TEST=don't crash on startup

http://codereview.chromium.org/6355003/

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@71444 0039d316-1c4b-4281-b951-d872f2087c98