Add ShellDelegate, MediaDelegate and KeyboardUI stubs to mus ash

ash/mus/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 47 matching lines @@
     "screenlock_layout.h",
     "shadow.cc",
     "shadow.h",
     "shadow_controller.cc",
     "shadow_controller.h",
     "shelf_layout_impl.cc",
     "shelf_layout_impl.h",
     "shelf_layout_manager.cc",
     "shelf_layout_manager.h",
     "shelf_layout_manager_delegate.h",
+    "shell_delegate_mus.cc",
+    "shell_delegate_mus.h",
     "status_layout_manager.cc",
     "status_layout_manager.h",
     "user_window_controller_impl.cc",
     "user_window_controller_impl.h",
     "window_manager.cc",
     "window_manager.h",
     "window_manager_application.cc",
     "window_manager_application.h",
     "window_manager_observer.h",
   ]
@@ skipping 122 matching lines @@
     "//ui/gfx/geometry",
     "//ui/gfx/geometry/mojo",
     "//ui/views/mus",
   ]
 
   data_deps = [
     ":mus",
     "//mash/quick_launch",
   ]
 }