Do not switch to a high-cost connection that is not receiving

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 f94972fb9daa93bc7e76c0096d8743ff7a4b0ca4..2dc9deaddb311b89d6816c472265412444adf7b9 100644
--- a/webrtc/p2p/base/port.h
+++ b/webrtc/p2p/base/port.h
@@ -553,6 +553,8 @@ class Connection : public CandidatePairInterface,
   int64_t last_ping_response_received() const {
     return last_ping_response_received_;
   }
+  // Used to check if any STUN ping response has been received.
+  int rtt_samples() const { return rtt_samples_; }
 
   // Called whenever a valid ping is received on this connection.  This is
   // public because the connection intercepts the first ping for us.