Mus Demo: Demonstrate external window mode

services/ui/demo/BUILD.gn

Index: services/ui/demo/BUILD.gn
diff --git a/services/ui/demo/BUILD.gn b/services/ui/demo/BUILD.gn
index 837da1fed2aa6bc7a4d608a1e37b13d6f245be00..15b5438089056c20eb39b567f84f08cff6964672 100644
--- a/services/ui/demo/BUILD.gn
+++ b/services/ui/demo/BUILD.gn
@@ -2,6 +2,7 @@
 # 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("//services/catalog/public/tools/catalog.gni")
 import("//services/service_manager/public/cpp/service.gni")
 import("//services/service_manager/public/service_manifest.gni")
@@ -12,12 +13,22 @@ source_set("lib") {
   sources = [
     "mus_demo.cc",
     "mus_demo.h",
-    "mus_demo_internal.cc",
-    "mus_demo_internal.h",
     "window_tree_data.cc",
     "window_tree_data.h",
   ]
 
+  if (use_ozone && !is_chromeos) {
+    sources += [
+      "mus_demo_external.cc",
+      "mus_demo_external.h",
+    ]
+  } else {
+    sources += [
+      "mus_demo_internal.cc",
+      "mus_demo_internal.h",
+    ]
+  }
+
   public_deps = [
     "//services/service_manager/public/cpp:sources",
     "//skia",
@@ -38,9 +49,15 @@ source_set("lib") {
 }
 
 service("mus_demo") {
-  sources = [
-    "main.cc",
-  ]
+  if (use_ozone && !is_chromeos) {
+    sources = [
+      "main_external.cc",
+    ]
+  } else {
+    sources = [
+      "main_internal.cc",
+    ]
+  }
 
   deps = [
     ":lib",