Creates BackgroundShell and uses it in test

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("//testing/test.gni")
 import("//tools/grit/repack.gni")
 
@@ skipping 114 matching lines @@
     deps = [
       "//mojo/gles2",
     ]
   }
 }
 
 group("tests") {
   testonly = true
 
   deps = [
-    ":views_apptests",
+    ":views_mus_unittests",
   ]
 }
 
-mojo_native_application("views_apptests") {
+test("views_mus_unittests") {
   testonly = true
 
-  configs = [ "//build/config:precompiled_headers" ]
+  configs += [ "//build/config:precompiled_headers" ]
 
   # TODO(sky): add more files.
   sources = [
+    "../run_all_unittests.cc",
+    "../run_all_unittests.h",
     "../widget/native_widget_unittest.cc",
     "../widget/root_view_unittest.cc",
     "../widget/widget_unittest.cc",
     "platform_test_helper_mus.cc",
+    "run_all_unittests_mus.cc",
   ]
 
   deps = [
     ":mus",
     "//base",
     "//base:i18n",
     "//base/test:test_support",
     "//cc",
-    "//mojo/shell/public/cpp:test_support",
+    "//mojo/shell/background:lib",
+    "//mojo/shell/background:main",
+    "//mojo/shell/public/cpp:sources",
     "//skia",
     "//testing/gtest",
     "//third_party/icu",
     "//ui/accessibility",
     "//ui/aura",
     "//ui/aura:test_support",
     "//ui/base",
     "//ui/base:test_support",
     "//ui/base/ime",
     "//ui/compositor:test_support",
@@ skipping 45 matching lines @@
 }
 
 group("for_component") {
   public_deps = [
     ":mus",
   ]
   deps = [
     "//mojo/gles2",
   ]
 }