Remove "Default Address Family" behavior from the HostResolver.

net/dns/host_resolver.h

Index: net/dns/host_resolver.h
diff --git a/net/dns/host_resolver.h b/net/dns/host_resolver.h
index 0203dc9a5d9650600ec10d6fa73e08efd4f3f45a..0fe96596cf50446753084685870c18df40c076da 100644
--- a/net/dns/host_resolver.h
+++ b/net/dns/host_resolver.h
@@ -167,13 +167,6 @@ class NET_EXPORT HostResolver {
   // has already run or the request was canceled.
   virtual void CancelRequest(RequestHandle req) = 0;
 
-  // Sets the default AddressFamily to use when requests have left it
-  // unspecified. For example, this could be used to restrict resolution
-  // results to AF_INET by passing in ADDRESS_FAMILY_IPV4, or to
-  // AF_INET6 by passing in ADDRESS_FAMILY_IPV6.
-  virtual void SetDefaultAddressFamily(AddressFamily address_family) {}
-  virtual AddressFamily GetDefaultAddressFamily() const;
-
   // Enable or disable the built-in asynchronous DnsClient.
   virtual void SetDnsClientEnabled(bool enabled);