Fix ash 'gn check' errors; whitelist target.

ash/mus/BUILD.gn

 # Copyright 2016 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/tools/bindings/mojom.gni")
 import("//tools/grit/repack.gni")
 
 source_set("lib") {
   sources = [
     "shelf_delegate_mus.cc",
     "shelf_delegate_mus.h",
     "shell_delegate_mus.cc",
     "shell_delegate_mus.h",
     "stub_context_factory.cc",
     "stub_context_factory.h",
     "sysui_application.cc",
     "sysui_application.h",
   ]
 
   deps = [
     "//ash",
+    "//cc",
+    "//cc/surfaces",
     "//components/mus/common",
     "//components/mus/public/cpp",
     "//components/mus/public/interfaces",
     "//components/user_manager",
     "//mash/wm/public/interfaces",
     "//mojo/common:common_base",
     "//mojo/converters/geometry",
     "//mojo/converters/input_events",
     "//mojo/services/tracing/public/cpp",
     "//mojo/shell/public/cpp",
@@ skipping 12 matching lines @@
   ]
 }
 
 mojo_native_application("mus") {
   output_name = "ash_sysui"
   sources = [
     "main.cc",
   ]
   deps = [
     ":lib",
+    "//mojo/shell/public/cpp",
   ]
 }