Allow parallel creation of windows

services/ui/demo/mus_demo_external.h

 // 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 <memory>
 #include <vector>
 
@@ skipping 11 matching lines @@
   ~MusDemoExternal() final;
 
  private:
   void OpenNewWindow();
 
   // ui::demo::MusDemo:
   void OnStartImpl() final;
   std::unique_ptr<aura::WindowTreeClient> CreateWindowTreeClient() final;
 
   // aura::WindowTreeClientDelegate:
-  void OnEmbed(std::unique_ptr<aura::WindowTreeHostMus> window_tree_host) final;
+  void OnRootWindowEmbed(aura::WindowTreeHostMus* window_tree_host) final;

[fwang, 2017/03/15 14:37:56]

What about OnEmbedRootReady, to be consistent with OnEmbedRootDestroyed?

I guess the OnEmbed in the parent class should be final.

[msisov, 2017/03/16 08:17:52]

Done.

   void OnEmbedRootDestroyed(aura::WindowTreeHostMus* window_tree_host) final;
 
   size_t initialized_windows_count_ = 0;
 
   size_t number_of_windows_ = 1;
 
+  std::vector<std::unique_ptr<aura::WindowTreeHostMus>>
+      window_tree_host_mus_list_;

[fwang, 2017/03/15 14:37:56]

I think you can just keep this in WindowTreeData.

[msisov, 2017/03/16 08:17:52]

Done.

+
   DISALLOW_COPY_AND_ASSIGN(MusDemoExternal);
 };
 
 }  // namespace demo
 }  // namespace ui
 
 #endif  // SERVICES_UI_DEMO_MUS_DEMO_EXTERNAL_H_