Implement Turn/Turn first logic for connection selection.

talk/app/webrtc/peerconnectioninterface.h

Index: talk/app/webrtc/peerconnectioninterface.h
diff --git a/talk/app/webrtc/peerconnectioninterface.h b/talk/app/webrtc/peerconnectioninterface.h
index 93f6241156e691ece8f2d19d544bb25499c37e05..6d554dfda548a45f501ca15e66e9373f192b65be 100644
--- a/talk/app/webrtc/peerconnectioninterface.h
+++ b/talk/app/webrtc/peerconnectioninterface.h
@@ -259,6 +259,7 @@ class PeerConnectionInterface : public rtc::RefCountInterface {
     ContinualGatheringPolicy continual_gathering_policy;
     std::vector<rtc::scoped_refptr<rtc::RTCCertificate>> certificates;
     bool disable_prerenderer_smoothing;
+    bool ping_most_likely_candidate_pair_first;

[pthatcher1, 2016/01/27 19:59:58]

I better name might be prioritize_most_likely_ice_candidate_pairs_.

[guoweis_webrtc, 2016/02/29 18:03:00]

Done.

     RTCConfiguration()
         : type(kAll),
           bundle_policy(kBundlePolicyBalanced),
@@ -269,7 +270,8 @@ class PeerConnectionInterface : public rtc::RefCountInterface {
           ice_connection_receiving_timeout(kUndefined),
           ice_backup_candidate_pair_ping_interval(kUndefined),
           continual_gathering_policy(GATHER_ONCE),
-          disable_prerenderer_smoothing(false) {}
+          disable_prerenderer_smoothing(false),
+          ping_most_likely_candidate_pair_first(false) {}
   };
 
   struct RTCOfferAnswerOptions {