mash: Add a launch-test for ash_sysui.

mash/wm/BUILD.gn

 # Copyright 2015 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("//build/config/ui.gni")
 import("//mojo/public/mojo_application.gni")
 import("//mojo/public/mojo_application_manifest.gni")
 import("//mojo/public/tools/bindings/mojom.gni")
 import("//tools/grit/repack.gni")
 
@@ skipping 153 matching lines @@
     "//ui/base",
     "//ui/events",
     "//ui/gfx:test_support",
     "//ui/gfx/geometry",
     "//ui/mojo/geometry:interfaces",
     "//ui/mojo/geometry:util",
   ]
 
   data_deps = [
     ":wm",
+    "//ash/mus",
     "//mash/quick_launch",
   ]
 }