Mus Demo: Demonstrate external window mode

services/ui/demo/mus_demo_external.h

Index: services/ui/demo/mus_demo_external.h
diff --git a/services/ui/demo/mus_demo_external.h b/services/ui/demo/mus_demo_external.h
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+// Copyright 2017 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.
+
+#ifndef SERVICES_UI_DEMO_MUS_DEMO_EXTERNAL_H_
+#define SERVICES_UI_DEMO_MUS_DEMO_EXTERNAL_H_
+
+#include "services/ui/demo/mus_demo.h"
+#include "services/ui/public/interfaces/window_tree_host.mojom.h"
+
+namespace ui {
+namespace demo {
+
+class MusDemoExternal : public MusDemo {
+ public:
+  MusDemoExternal();
+
+ private:
+  void OnStartImpl() override;
+
+  // aura::WindowTreeClientDelegate:
+  void OnEmbed(
+      std::unique_ptr<aura::WindowTreeHostMus> window_tree_host) override;
+  void OnEmbedRootDestroyed(aura::WindowTreeHostMus* window_tree_host) override;
+
+  mojom::WindowTreeHostFactoryPtr window_tree_host_factory_;
+
+  DISALLOW_COPY_AND_ASSIGN(MusDemoExternal);
+};
+
+}  // namespace demo
+}  // namespace aura
+
+#endif  // SERVICES_UI_DEMO_MUS_DEMO_EXTERNAL_H_