Fix IT2Me protocol error connecting to old hosts.

remoting/protocol/negotiating_host_authenticator.cc

 // Copyright 2013 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #include "remoting/protocol/negotiating_host_authenticator.h"
 
 #include <algorithm>
 #include <sstream>
 #include <utility>
 
@@ skipping 213 matching lines @@
       break;
     }
 
     case Method::SHARED_SECRET_SPAKE2_CURVE25519:
       current_authenticator_ = Spake2Authenticator::CreateForHost(
           local_id_, remote_id_, local_cert_, local_key_pair_,
           shared_secret_hash_, preferred_initial_state);
       resume_callback.Run();
       break;
 
+    case Method::SHARED_SECRET_PLAIN_SPAKE2_P224:
     case Method::SHARED_SECRET_SPAKE2_P224:
       current_authenticator_ = V2Authenticator::CreateForHost(
           local_cert_, local_key_pair_, shared_secret_hash_,
           preferred_initial_state);
       resume_callback.Run();
       break;
   }
 }
 
 }  // namespace protocol
 }  // namespace remoting