Only try to pair protocol matching candidates for creating connections.

webrtc/p2p/base/turnport.h

Index: webrtc/p2p/base/turnport.h
diff --git a/webrtc/p2p/base/turnport.h b/webrtc/p2p/base/turnport.h
index 62e3c41580a15671f445e9aa0b9425500d59e514..673a5a2c3809c28de65af324b894cc5bb6069202 100644
--- a/webrtc/p2p/base/turnport.h
+++ b/webrtc/p2p/base/turnport.h
@@ -107,6 +107,10 @@ class TurnPort : public Port {
                             const rtc::PacketTime& packet_time);
 
   virtual void OnReadyToSend(rtc::AsyncPacketSocket* socket);
+  virtual bool ProtocolMatch(const std::string& protocol) const {
+    // Turn port only connects to UDP candidates.
+    return protocol == UDP_PROTOCOL_NAME;
+  }
 
   void OnSocketConnect(rtc::AsyncPacketSocket* socket);
   void OnSocketClose(rtc::AsyncPacketSocket* socket, int error);