Stop calling deprecated version of "CreateIceCandidate".

remoting/host/cast_extension_session.cc

Index: remoting/host/cast_extension_session.cc
diff --git a/remoting/host/cast_extension_session.cc b/remoting/host/cast_extension_session.cc
index d43beff9a49e244e39b2277aca2f015f9e07ed20..65e003cbbd91e991bc324d8f5c11cdf44486ad56 100644
--- a/remoting/host/cast_extension_session.cc
+++ b/remoting/host/cast_extension_session.cc
@@ -389,7 +389,8 @@ bool CastExtensionSession::ParseAndAddICECandidate(
   }
 
   rtc::scoped_ptr<webrtc::IceCandidateInterface> candidate(
-      webrtc::CreateIceCandidate(sdp_mid, sdp_mlineindex, candidate_str));
+      webrtc::CreateIceCandidate(sdp_mid, sdp_mlineindex, candidate_str,
+                                 nullptr));
   if (!candidate.get()) {
     LOG(ERROR)
         << "Invalid Cast Extension Message (could not create candidate).";