Connect mojom::DisplayController from ash to ui.

services/ui/service.h

 // 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.
 
 #ifndef SERVICES_UI_SERVICE_H_
 #define SERVICES_UI_SERVICE_H_
 
 #include <stdint.h>
 
 #include <map>
@@ skipping 149 matching lines @@
               mojom::WindowServerTestRequest request) override;
 
   std::unique_ptr<ws::WindowServer> window_server_;
   std::unique_ptr<ui::PlatformEventSource> event_source_;
   tracing::Provider tracing_;
   using PendingRequests = std::vector<std::unique_ptr<PendingRequest>>;
   PendingRequests pending_requests_;
 
   UserIdToUserState user_id_to_user_state_;
 
-  // Provides input-device information via Mojo IPC.
+  // Provides input-device information via Mojo IPC. Registers Mojo interfaces
+  // and must outlive shell::InterfaceRegistry.
   InputDeviceServer input_device_server_;
 
   bool test_config_;
 #if defined(USE_OZONE)
   std::unique_ptr<ui::ClientNativePixmapFactory> client_native_pixmap_factory_;
 #endif
 
+  // Manages display hardware and handles display management. May register Mojo
+  // interfaces and must outlive shell::InterfaceRegistry.
   std::unique_ptr<display::PlatformScreen> platform_screen_;
+
   std::unique_ptr<ws::TouchController> touch_controller_;
   IMERegistrarImpl ime_registrar_;
   IMEServerImpl ime_server_;
 
   DISALLOW_COPY_AND_ASSIGN(Service);
 };
 
 }  // namespace ui
 
 #endif  // SERVICES_UI_SERVICE_H_