Connect mojom::DisplayController from ash to ui.

services/ui/service.h

Index: services/ui/service.h
diff --git a/services/ui/service.h b/services/ui/service.h
index a0fb21a33c28f233f4269fdc0981e1c403cc56fc..9e1b6b2d2168a8479f5743e0186ee9662f82dfa0 100644
--- a/services/ui/service.h
+++ b/services/ui/service.h
@@ -167,7 +167,8 @@ class Service
 
   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_;
@@ -175,7 +176,10 @@ class Service
   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_;