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

net/dns/host_resolver_impl.h

Index: net/dns/host_resolver_impl.h
diff --git a/net/dns/host_resolver_impl.h b/net/dns/host_resolver_impl.h
index 65b5c0b5776fa96cfdd889787010847f8944b548..f78d39ecaa0fc457363b7faa94c0b31444469b37 100644
--- a/net/dns/host_resolver_impl.h
+++ b/net/dns/host_resolver_impl.h
@@ -158,9 +158,6 @@ class NET_EXPORT HostResolverImpl
       const PersistCallback& persist_callback,
       std::unique_ptr<const base::Value> old_data) override;
 
-  void SetDefaultAddressFamily(AddressFamily address_family) override;
-  AddressFamily GetDefaultAddressFamily() const override;
-
   void SetNoIPv6OnWifi(bool no_ipv6_on_wifi) override;
   bool GetNoIPv6OnWifi() override;
 
@@ -356,10 +353,6 @@ class NET_EXPORT HostResolverImpl
   // Number of consecutive failures of DnsTask, counted when fallback succeeds.
   unsigned num_dns_failures_;
 
-  // Address family to use when the request doesn't specify one. See
-  // http://crbug.com/696569 for why the option is needed.
-  AddressFamily default_address_family_;
-
   // True if IPv6 should not be attempted when on a WiFi connection. See
   // https://crbug.com/696569 for further context.
   bool assume_ipv6_failure_on_wifi_;