Adds a new error (ERR_NETWORK_ACCESS_DENIED) for when network
operations return an access is denied error.
This is in preparation for adding new error text suggesting
a firewall may be causing the problem, which would be a little
embarrassing to do when an SSPI logon fails, or when trying to
open a local file one doesn't have permissions to.
TEST=Install firewall, block Chrome, verify that you get
ERR_NETWORK_ACCESS_DENIED. Unblock it, fail an SSPI logon
(Or any other event that should generate an ERR_ACCESS_DENIED)
and verify that you still get an ERR_ACCESS_DENIED.