Add //ui/* to "gn check"

ui/views/mus/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("//tools/grit/repack.gni")
 
 component("mus") {
   output_name = "ui_views_mus_lib"
 
   sources = [
@@ skipping 53 matching lines @@
     "//ui/aura",
     "//ui/compositor",
     "//ui/events",
     "//ui/events:events_base",
     "//ui/gfx",
     "//ui/gfx/geometry",
     "//ui/gl",
     "//ui/mojo/ime:interfaces_cpp_sources",
     "//ui/mojo/init",
     "//ui/native_theme",
+    "//ui/platform_window",
     "//ui/views",
     "//ui/wm",
   ]
 
   data_deps = [
     "//components/resource_provider",
   ]
 
   if (is_linux && !is_android) {
     deps += [ "//components/font_service/public/cpp" ]
@@ skipping 34 matching lines @@
 }
 
 group("for_component") {
   public_deps = [
     ":mus",
   ]
   deps = [
     "//mojo/gles2",
   ]
 }