Revert 121055 - Remove BeginSessionDeprecated.

remoting/proto/control.proto

-// Copyright (c) 2012 The Chromium Authors. All rights reserved.
+// Copyright (c) 2011 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.
 //
 // Protocol for control messages.
 
 syntax = "proto2";
 
 option optimize_for = LITE_RUNTIME;
 
 package remoting.protocol;
 
+// BeginSessionDeprecated is sent from host to client when the session
+// starts. Legacy clients expect to receive this message at the
+// beginning of each session. Current clients ignore it.
+//
+// TODO(sergeyu): Remove this message. See http://crbug.com/104670 .
+message LocalLoginStatusDeprecated {
+  optional bool success = 1;
+}
+message BeginSessionDeprecated {
+  optional LocalLoginStatusDeprecated login_status = 1;
+}