Add FakeDisplayDelegate for off device usage.

ui/ozone/platform/drm/host/drm_native_display_delegate.cc

Index: ui/ozone/platform/drm/host/drm_native_display_delegate.cc
diff --git a/ui/ozone/platform/drm/host/drm_native_display_delegate.cc b/ui/ozone/platform/drm/host/drm_native_display_delegate.cc
index 1563516b1075169db8f9889d686f8df9f332ebf0..d93d063e26fe15281480e0a556b395c5afea6b53 100644
--- a/ui/ozone/platform/drm/host/drm_native_display_delegate.cc
+++ b/ui/ozone/platform/drm/host/drm_native_display_delegate.cc
@@ -120,4 +120,9 @@ void DrmNativeDisplayDelegate::RemoveObserver(NativeDisplayObserver* observer) {
   observers_.RemoveObserver(observer);
 }
 
+display::VirtualDisplayController*
+DrmNativeDisplayDelegate::GetVirtualDisplayController() {
+  return nullptr;
+}
+
 }  // namespace ui