views/mus: Add support for child widgets.

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("//build/config/features.gni")
 import("//build/config/ui.gni")
 import("//mojo/public/mojo_application.gni")
 import("//mojo/public/mojo_application_manifest.gni")
 import("//testing/test.gni")
 import("//tools/grit/repack.gni")
@@ skipping 142 matching lines @@
   ]
 }
 
 test("views_mus_unittests") {
   testonly = true
 
   configs += [ "//build/config:precompiled_headers" ]
 
   # TODO(sky): add more files.
   sources = [
+    "../controls/native/native_view_host_aura_unittest.cc",
+    "../controls/native/native_view_host_test_base.cc",
+    "../controls/native/native_view_host_test_base.h",
+    "../controls/native/native_view_host_unittest.cc",
     "../view_targeter_unittest.cc",
+    "../widget/native_widget_aura_unittest.cc",
     "../widget/native_widget_unittest.cc",
     "../widget/widget_unittest.cc",
     "display_list_unittest.cc",
     "native_widget_mus_unittest.cc",
     "run_all_unittests_mus.cc",
     "screen_mus_unittest.cc",
     "window_manager_connection_unittest.cc",
   ]
 
   deps = [
@@ skipping 118 matching lines @@
   type = "exe"
   application_name = "views_mus_interactive_ui_tests"
   source = "interactive_ui_tests_manifest.json"
 }
 
 group("for_component") {
   public_deps = [
     ":mus",
   ]
 }