Remove first_message argument from AuthenticatorFactory::Create().

remoting/protocol/it2me_host_authenticator_factory.h

Index: remoting/protocol/it2me_host_authenticator_factory.h
diff --git a/remoting/protocol/it2me_host_authenticator_factory.h b/remoting/protocol/it2me_host_authenticator_factory.h
index 78957d262dba6dbdfcf4c5d614b2d652562e576b..6a1216462ec432d0b3e2248d6ad9e08524a615f2 100644
--- a/remoting/protocol/it2me_host_authenticator_factory.h
+++ b/remoting/protocol/it2me_host_authenticator_factory.h
@@ -32,8 +32,7 @@ class It2MeHostAuthenticatorFactory : public AuthenticatorFactory {
   // AuthenticatorFactory interface.
   scoped_ptr<Authenticator> CreateAuthenticator(
       const std::string& local_jid,
-      const std::string& remote_jid,
-      const buzz::XmlElement* first_message) override;
+      const std::string& remote_jid) override;
 
  private:
   std::string local_cert_;