Send back ping response if the ping comes from an unknown address.

webrtc/p2p/base/port.h

Index: webrtc/p2p/base/port.h
diff --git a/webrtc/p2p/base/port.h b/webrtc/p2p/base/port.h
index 01c45f26d8691303378766258c99cc7fefdde621..2f69f4945959a1fda3b81ae5cc2e93eb7edf045b 100644
--- a/webrtc/p2p/base/port.h
+++ b/webrtc/p2p/base/port.h
@@ -523,6 +523,8 @@ class Connection : public rtc::MessageHandler,
   // public because the connection intercepts the first ping for us.
   uint32_t last_ping_received() const { return last_ping_received_; }
   void ReceivedPing();
+  // Handles the binding request; sends a response if this is a valid request.
+  void HandleBindingRequest(IceMessage* msg);
 
   // Debugging description of this connection
   std::string ToDebugId() const;