[net/dns] Add test DualFamilyLocalhost and fix it when DnsClient enabled.
On some platforms, listening on "localhost" binds to the IPv6 loopback
(::1), even if there's no global IPv6 connectivity. In such situations,
HostResolverImpl restricts lookups to IPv4 (AF_INET) for performance
reasons, but then navigating to http://localhost results in "connection
refused".
HostResolverProc has a workaround for this situation. This CL adds a
test for this behavior and replicates the workaround in
HostResolverImpl::ServeFromHosts (for the built-in asynchronous DNS).
BUG=224215
Review URL: https://codereview.chromium.org/14208010
git-svn-id: svn://svn.chromium.org/chrome/trunk/src@194663 0039d316-1c4b-4281-b951-d872f2087c98
3 files changed
