Revert "Add back "default address family" to HostResolver"

net/dns/host_resolver.cc

Index: net/dns/host_resolver.cc
diff --git a/net/dns/host_resolver.cc b/net/dns/host_resolver.cc
index 656e7a8b52929420badcaca72117b03d83ccfbaa..1f6dcf9b65ef33a3ee1d203f4d21525f5eacfe00 100644
--- a/net/dns/host_resolver.cc
+++ b/net/dns/host_resolver.cc
@@ -132,14 +132,6 @@ void HostResolver::InitializePersistence(
     const PersistCallback& persist_callback,
     std::unique_ptr<const base::Value> old_data) {}
 
-void HostResolver::SetDefaultAddressFamily(AddressFamily address_family) {
-  NOTREACHED();
-}
-
-AddressFamily HostResolver::GetDefaultAddressFamily() const {
-  return ADDRESS_FAMILY_UNSPECIFIED;
-}
-
 void HostResolver::SetNoIPv6OnWifi(bool no_ipv6_on_wifi) {
   NOTREACHED();
 }