Add back "default address family" to HostResolver

net/dns/host_resolver_impl.h

 // Copyright (c) 2012 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #ifndef NET_DNS_HOST_RESOLVER_IMPL_H_
 #define NET_DNS_HOST_RESOLVER_IMPL_H_
 
 #include <stddef.h>
 #include <stdint.h>
 
@@ skipping 140 matching lines @@
   // returned to indicate how stale (or not) it is.
   int ResolveStaleFromCache(const RequestInfo& info,
                             AddressList* addresses,
                             HostCache::EntryStaleness* stale_info,
                             const NetLogWithSource& source_net_log);
 
   void InitializePersistence(
       const PersistCallback& persist_callback,
       std::unique_ptr<const base::Value> old_data) override;
 
+  void SetDefaultAddressFamily(AddressFamily address_family) override;
+  AddressFamily GetDefaultAddressFamily() const override;
+
   void set_proc_params_for_test(const ProcTaskParams& proc_params) {
     proc_params_ = proc_params;
   }
 
  protected:
   // Just like the public constructor, but allows the task runner used for
   // blocking tasks to be specified. Intended for testing only.
   HostResolverImpl(const Options& options,
                    NetLog* net_log,
                    scoped_refptr<base::TaskRunner> worker_task_runner);
@@ skipping 168 matching lines @@
   // If present, used by DnsTask and ServeFromHosts to resolve requests.
   std::unique_ptr<DnsClient> dns_client_;
 
   // True if received valid config from |dns_config_service_|. Temporary, used
   // to measure performance of DnsConfigService: http://crbug.com/125599
   bool received_dns_config_;
 
   // 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. This is used
+  // only to disable IPv6 in Cronet, and can be removed when support for the

[xunjieli, 2017/02/27 15:41:38]

same here.

[mgersh, 2017/02/28 16:49:06]

Done.

+  // option is no longer needed. See http://crbug.com/696569.
+  AddressFamily default_address_family_;
+
   // True if DnsConfigService detected that system configuration depends on
   // local IPv6 connectivity. Disables probing.
   bool use_local_ipv6_;
 
   base::TimeTicks last_ipv6_probe_time_;
   bool last_ipv6_probe_result_;
 
   // True iff ProcTask has successfully resolved a hostname known to have IPv6
   // addresses using ADDRESS_FAMILY_UNSPECIFIED. Reset on IP address change.
   bool resolved_known_ipv6_hostname_;
@@ skipping 31 matching lines @@
 // This function is only exposed so it can be unit-tested.
 // TODO(tfarina): It would be better to change the tests so this function
 // gets exercised indirectly through HostResolverImpl.
 NET_EXPORT_PRIVATE bool ResolveLocalHostname(base::StringPiece host,
                                              uint16_t port,
                                              AddressList* address_list);
 
 }  // namespace net
 
 #endif  // NET_DNS_HOST_RESOLVER_IMPL_H_