Revert of Quit the message loop by default in ShellConnectionLost when ApplicationRunner is used

ash/mus/sysui_application.cc

 // Copyright 2016 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 "ash/mus/sysui_application.h"
 
 #include "ash/desktop_background/desktop_background_controller.h"
 #include "ash/host/ash_window_tree_host_init_params.h"
 #include "ash/host/ash_window_tree_host_platform.h"
 #include "ash/mus/keyboard_ui_mus.h"
 #include "ash/mus/shell_delegate_mus.h"
 #include "ash/mus/stub_context_factory.h"
 #include "ash/root_window_settings.h"
 #include "ash/shell.h"
 #include "ash/shell_init_params.h"
 #include "ash/shell_window_ids.h"
 #include "base/bind.h"
 #include "base/files/file_path.h"
+#include "base/message_loop/message_loop.h"
 #include "base/path_service.h"
 #include "base/threading/sequenced_worker_pool.h"
 #include "components/mus/public/cpp/property_type_converters.h"
 #include "mash/wm/public/interfaces/ash_window_type.mojom.h"
 #include "mash/wm/public/interfaces/container.mojom.h"
 #include "ui/aura/env.h"
 #include "ui/base/resource/resource_bundle.h"
 #include "ui/base/ui_base_paths.h"
 #include "ui/message_center/message_center.h"
 #include "ui/platform_window/stub/stub_window.h"
@@ skipping 252 matching lines @@
                                   const mojo::Identity& identity,
                                   uint32_t id) {
   ash_init_.reset(new AshInit());
   ash_init_->Initialize(connector);
 }
 
 bool SysUIApplication::AcceptConnection(mojo::Connection* connection) {
   return true;
 }
 
+void SysUIApplication::ShellConnectionLost() {
+  base::MessageLoop::current()->QuitWhenIdle();
+}
+
 }  // namespace sysui
 }  // namespace ash