Connect mojom::DisplayController from ash to ui.

ash/mus/accelerators/accelerator_controller_delegate_mus.cc

Index: ash/mus/accelerators/accelerator_controller_delegate_mus.cc
diff --git a/ash/mus/accelerators/accelerator_controller_delegate_mus.cc b/ash/mus/accelerators/accelerator_controller_delegate_mus.cc
index d935fc7e216c10373c6ebb560098a053561c8393..6cd38390c25d9b959fead4574e1b68447c95d073 100644
--- a/ash/mus/accelerators/accelerator_controller_delegate_mus.cc
+++ b/ash/mus/accelerators/accelerator_controller_delegate_mus.cc
@@ -6,6 +6,7 @@
 
 #include "base/logging.h"
 #include "mash/public/interfaces/launchable.mojom.h"
+#include "services/ui/public/interfaces/display/display_controller.mojom.h"
 
 namespace ash {
 namespace mus {
@@ -50,7 +51,12 @@ bool AcceleratorControllerDelegateMus::HandlesAction(AcceleratorAction action) {
       return false;
 
 #if defined(OS_CHROMEOS)
-    case DEBUG_ADD_REMOVE_DISPLAY:
+    case DEBUG_ADD_REMOVE_DISPLAY: {
+      display::mojom::DisplayControllerPtr display_controller;
+      connector_->ConnectToInterface("mojo:ui", &display_controller);
+      display_controller->ToggleVirtualDisplay();
+      break;
+    }
     case DEBUG_TOGGLE_UNIFIED_DESKTOP:
     case DISABLE_GPU_WATCHDOG:
     case LOCK_PRESSED: