Fix WebRTC transport to use single offer-answer exchange instead of two.

remoting/protocol/webrtc_connection_to_client.h

Index: remoting/protocol/webrtc_connection_to_client.h
diff --git a/remoting/protocol/webrtc_connection_to_client.h b/remoting/protocol/webrtc_connection_to_client.h
index 34f51ba9fcf4a0421016d0e04f3106a4b9d7b494..d5ce65f269eb5b98245b4421c27f0c7840c60611 100644
--- a/remoting/protocol/webrtc_connection_to_client.h
+++ b/remoting/protocol/webrtc_connection_to_client.h
@@ -11,6 +11,7 @@
 #include <string>
 
 #include "base/macros.h"
+#include "base/memory/weak_ptr.h"
 #include "base/threading/thread_checker.h"
 #include "remoting/protocol/channel_dispatcher_base.h"
 #include "remoting/protocol/connection_to_client.h"
@@ -75,6 +76,8 @@ class WebrtcConnectionToClient : public ConnectionToClient,
   std::unique_ptr<HostControlDispatcher> control_dispatcher_;
   std::unique_ptr<HostEventDispatcher> event_dispatcher_;
 
+  base::WeakPtrFactory<WebrtcConnectionToClient> weak_factory_;
+
   DISALLOW_COPY_AND_ASSIGN(WebrtcConnectionToClient);
 };