chromeos: Remove old LockScreen signal.

chrome/browser/chromeos/dbus/screen_lock_service_provider.cc

 // Copyright 2014 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 "chrome/browser/chromeos/dbus/screen_lock_service_provider.h"
 
 #include "ash/shell.h"
 #include "ash/wm/lock_state_controller.h"
 #include "base/bind.h"
 #include "chrome/browser/chromeos/login/screen_locker.h"
@@ skipping 25 matching lines @@
                                            bool success) {
   if (!success) {
     LOG(ERROR) << "Failed to export " << interface_name << "."
                << method_name;
   }
 }
 
 void ScreenLockServiceProvider::LockScreen(
     dbus::MethodCall* method_call,
     dbus::ExportedObject::ResponseSender response_sender) {
+  // Please add any additional logic to ScreenLocker::HandleLockScreenRequest()
+  // instead of placing it here.
   ScreenLocker::HandleLockScreenRequest();
-  ash::Shell::GetInstance()->lock_state_controller()->OnStartingLock();
   response_sender.Run(dbus::Response::FromMethodCall(method_call));
 }
 
 }  // namespace chromeos