Add ufrag to the ICE candidate signaling.

webrtc/p2p/base/p2ptransportchannel.h

Index: webrtc/p2p/base/p2ptransportchannel.h
diff --git a/webrtc/p2p/base/p2ptransportchannel.h b/webrtc/p2p/base/p2ptransportchannel.h
index 7d9b6121a2a9556b58d1ed8a22eef3e7f89cb15a..430535e957e7a29fd8d3c99da85f3df81388bd03 100644
--- a/webrtc/p2p/base/p2ptransportchannel.h
+++ b/webrtc/p2p/base/p2ptransportchannel.h
@@ -259,6 +259,8 @@ class P2PTransportChannel : public TransportChannelImpl,
   uint32_t last_ping_sent_ms_ = 0;
   bool gather_continually_ = false;
   int weak_ping_delay_ = WEAK_PING_DELAY;
+  // Keep a set of old remote ufrags so that we know whether a ufrag is new.
+  std::set<std::string> old_remote_ufrags_;

[pthatcher1, 2015/12/04 20:43:50]

I think a good name for this would be remote_generations_.  And then maybe store
a struct of IceGenerations like this:

struct IceGeneration {
  std::string ufrag;
}

Then later, we could possibly add other things, like pwd.

Additionally, I think we should put the current one in there and have
remote_ufrag() and remote_pwd() getters return remote_generations_[0]...

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

Done. added the pwd there too.

 
   RTC_DISALLOW_COPY_AND_ASSIGN(P2PTransportChannel);
 };