Only try to pair protocol matching candidates for creating connections.

webrtc/p2p/base/tcpport.h

Index: webrtc/p2p/base/tcpport.h
diff --git a/webrtc/p2p/base/tcpport.h b/webrtc/p2p/base/tcpport.h
index a64c5eeab94ff6193bc7e3c206aa36b9ab920a46..1659257803a9d49950815ec1a59402cd0f221f7e 100644
--- a/webrtc/p2p/base/tcpport.h
+++ b/webrtc/p2p/base/tcpport.h
@@ -55,6 +55,9 @@ class TCPPort : public Port {
   virtual int GetOption(rtc::Socket::Option opt, int* value);
   virtual int SetOption(rtc::Socket::Option opt, int value);
   virtual int GetError();
+  virtual bool ProtocolMatch(const std::string& protocol) const {
+    return protocol == TCP_PROTOCOL_NAME || protocol == SSLTCP_PROTOCOL_NAME;
+  }
 
  protected:
   TCPPort(rtc::Thread* thread,