Add ufrag to the ICE candidate signaling.

talk/app/webrtc/webrtcsdp.cc

Index: talk/app/webrtc/webrtcsdp.cc
diff --git a/talk/app/webrtc/webrtcsdp.cc b/talk/app/webrtc/webrtcsdp.cc
index fceaaf4e32e3b63f444d364061e9fafbb6875cf8..ac33e0968fa2cf510012f43313e5b0361e21f631 100644
--- a/talk/app/webrtc/webrtcsdp.cc
+++ b/talk/app/webrtc/webrtcsdp.cc
@@ -1758,6 +1758,9 @@ void BuildCandidate(const std::vector<Candidate>& candidates,
 
     // Extensions
     os << kAttributeCandidateGeneration << " " << it->generation();
+    if (!it->username().empty()) {
+      os << " " << kAttributeCandidateUsername << " " << it->username();

[pthatcher1, 2015/12/04 20:43:49]

This would make it "username", but it's not really a username.  It's a "username
fragment".  So we should probably make the string "ufrag".  Maybe call it
kAttributeCandidateUsernameFragment

[honghaiz3, 2015/12/09 23:57:54]

I just used the one kAttributeUfrag which is "ice-ufrag", so that it matches the
one in the offer/answer.

+    }
 
     AddLine(os.str(), message);
   }
@@ -2667,7 +2670,6 @@ bool ParseContent(const std::string& message,
   // Update the candidates with the media level "ice-pwd" and "ice-ufrag".
   for (Candidates::iterator it = candidates_orig.begin();
        it != candidates_orig.end(); ++it) {

[pthatcher1, 2015/12/04 20:43:49]

Since this is parsing candidates in the SDP (not trickled), shouldn't we assert
that it's empty or that it matches the value in the transport description?

[honghaiz3, 2015/12/09 23:57:54]

Yes. Thanks. 

-    ASSERT((*it).username().empty());
     (*it).set_username(transport->ice_ufrag);
     ASSERT((*it).password().empty());
     (*it).set_password(transport->ice_pwd);