Revert 39998 - Revert 39996 Refine IPv6 probe to require that the client has...

net/base/host_resolver_impl.h

Index: net/base/host_resolver_impl.h
===================================================================
--- net/base/host_resolver_impl.h	(revision 40097)
+++ net/base/host_resolver_impl.h	(working copy)
@@ -88,10 +88,13 @@
   virtual void AddObserver(HostResolver::Observer* observer);
   virtual void RemoveObserver(HostResolver::Observer* observer);
 
-  virtual void SetDefaultAddressFamily(AddressFamily address_family) {
-    default_address_family_ = address_family;
-  }
+  // Set address family, and disable IPv6 probe support.
+  virtual void SetDefaultAddressFamily(AddressFamily address_family);
 
+  // Continuously observe whether IPv6 is supported, and set the allowable
+  // address family to IPv4 iff IPv6 is not supported.
+  void ProbeIPv6Support();
+
   virtual HostResolverImpl* GetAsHostResolverImpl() { return this; }
 
   // TODO(eroman): hack for http://crbug.com/15513
@@ -244,6 +247,11 @@
 
   NetworkChangeNotifier* const network_change_notifier_;
 
+  // Indicate if probing is done after each network change event to set address
+  // family.
+  // When false, explicit setting of address family is used.
+  bool ipv6_probe_monitoring_;
+
   scoped_refptr<RequestsTrace> requests_trace_;
 
   DISALLOW_COPY_AND_ASSIGN(HostResolverImpl);