Add an explicit way of forcing the MDnsClient to listen on the network

net/dns/mdns_client.h

 // Copyright 2013 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_MDNS_CLIENT_H_
 #define NET_DNS_MDNS_CLIENT_H_
 
 #include <string>
 #include <vector>
 
@@ skipping 125 matching lines @@
 
   // Create a transaction that can be used to query either the MDns cache, the
   // network, or both for records of type |rrtype| and name |name|. |flags| is
   // defined by MDnsTransactionFlags.
   virtual scoped_ptr<MDnsTransaction> CreateTransaction(
       uint16 rrtype,
       const std::string& name,
       int flags,
       const MDnsTransaction::ResultCallback& callback) = 0;
 
+  virtual bool StartListening() = 0;
+
+  // Do not call this inside callbacks from related MDnsListener and
+  // MDnsTransaction objects.
+  virtual void StopListening() = 0;
+  virtual bool IsListening() const = 0;
+
   // Lazily create and return static instance for MDnsClient.
   static MDnsClient* GetInstance();
 
   // Set the global instance (for testing). MUST be called before the first call
   // to GetInstance.
   static void SetInstance(MDnsClient* instance);
 };
 
 }  // namespace net
 #endif  // NET_DNS_MDNS_CLIENT_H_