Add signaling to support ICE renomination.

webrtc/api/peerconnection.h

Index: webrtc/api/peerconnection.h
diff --git a/webrtc/api/peerconnection.h b/webrtc/api/peerconnection.h
index c4a9a60053db82ca9976340412334e70bae55a59..d3426e614c75dabd43222c6a79221b9bca60b504 100644
--- a/webrtc/api/peerconnection.h
+++ b/webrtc/api/peerconnection.h
@@ -239,6 +239,10 @@ class PeerConnection : public PeerConnectionInterface,
       const RTCOfferAnswerOptions& options,
       cricket::MediaSessionOptions* session_options);
 
+  void InitializeMediaSessionOptions(
+      bool is_offer,
+      cricket::MediaSessionOptions* session_options);
+
   // Helper function for options processing.
   // Deprecated.
   virtual void FinishOptionsForAnswer(
@@ -371,6 +375,12 @@ class PeerConnection : public PeerConnectionInterface,
   // This function should only be called from the worker thread.
   void StopRtcEventLog_w();
 
+  cricket::TransportOptions MakeTransportOptions() {
+    cricket::TransportOptions options;
+    options.ice_renomination = ice_renomination_;
+    return options;
+  }
+
   // Storing the factory as a scoped reference pointer ensures that the memory
   // in the PeerConnectionFactoryImpl remains available as long as the
   // PeerConnection is running. It is passed to PeerConnection as a raw pointer.
@@ -414,6 +424,8 @@ class PeerConnection : public PeerConnectionInterface,
 
   bool remote_peer_supports_msid_ = false;
 
+  bool ice_renomination_ = false;
+
   std::vector<rtc::scoped_refptr<RtpSenderProxyWithInternal<RtpSenderInternal>>>
       senders_;
   std::vector<