Fork the mojo shell interfaces used by Mandoline.

mojo/application/public/interfaces/BUILD.gn

 # 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.
 
 import("//third_party/mojo/src/mojo/public/tools/bindings/mojom.gni")
 
+# GYP version: mojo/mojo_base.gyp:mojo_application_bindings
 mojom("interfaces") {
   sources = [
-    "geometry.mojom",
+    "application.mojom",
+    "service_provider.mojom",
+    "shell.mojom",
   ]
 }
-
-source_set("util") {
-  sources = [
-    "geometry_util.h",
-  ]
-}