Mus Demo: Refactor code to prepare multiple windows in external mode

services/ui/demo/mus_demo.h

 // Copyright 2016 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_H_
 #define SERVICES_UI_DEMO_MUS_DEMO_H_
 
 #include <memory>
 
 #include "base/callback.h"
@@ skipping 26 matching lines @@
 // the window. Provides a simple way to demonstrate that the graphic stack works
 // as intended.
 class MusDemo : public service_manager::Service,
                 public aura::WindowTreeClientDelegate {
  public:
   MusDemo();
   ~MusDemo() override;
 
  protected:
   void AddPrimaryDisplay(const display::Display& display);
+
+  // These functions help to manage the list of WindowTreeData structures.
+  // AppendWindowTreeData is used to add an uninitialized structure at the end
+  // of the list. When a new WindowTreeHostMus is created and is sent to
+  // MusDemo (via OnWmNewDisplay or OnEmbed), the WindowTreeData is initialized
+  // by a call to InitWindowTreeData and the demo starts. When the destruction
+  // of the WindowTreeHostMus is announced to MusDemo (via OnWmDisplayRemoved
+  // or OnEmbedRootDestroyed), the corresponding WindowTreeData is removed by
+  // a call to RemoveWindowTreeData.
+  void AppendWindowTreeData(std::unique_ptr<WindowTreeData> window_tree_data);
   void InitWindowTreeData(
       std::unique_ptr<aura::WindowTreeHostMus> window_tree_host);
-  void CleanupWindowTreeData();
+  void RemoveWindowTreeData(aura::WindowTreeHostMus* window_tree_host);
+
+  aura::WindowTreeClient* window_tree_client() {
+    return window_tree_client_.get();
+  }
 
  private:
-  virtual void OnStartImpl(
-      std::unique_ptr<aura::WindowTreeClient>* window_tree_client,
-      std::unique_ptr<WindowTreeData>* window_tree_data) = 0;
+  virtual void OnStartImpl() = 0;
+  virtual std::unique_ptr<aura::WindowTreeClient> CreateWindowTreeClient() = 0;
+  bool HasPendingWindowTreeData() const;
 
   // service_manager::Service:
   void OnStart() override;
   bool OnConnect(const service_manager::ServiceInfo& remote_info,
                  service_manager::InterfaceRegistry* registry) override;
 
   // aura::WindowTreeClientDelegate:
   void OnEmbed(
       std::unique_ptr<aura::WindowTreeHostMus> window_tree_host) override;
   void OnUnembed(aura::Window* root) override;
   void OnEmbedRootDestroyed(aura::WindowTreeHostMus* window_tree_host) override;
   void OnLostConnection(aura::WindowTreeClient* client) override;
   void OnPointerEventObserved(const ui::PointerEvent& event,
                               aura::Window* target) override;
   aura::PropertyConverter* GetPropertyConverter() override;
 
   std::unique_ptr<aura::WindowTreeClient> window_tree_client_;
   std::unique_ptr<aura::Env> env_;
   std::unique_ptr<display::ScreenBase> screen_;
 
   std::unique_ptr<aura::client::DefaultCaptureClient> capture_client_;
   std::unique_ptr<::wm::WMState> wm_state_;
   std::unique_ptr<aura::PropertyConverter> property_converter_;
 
-  std::unique_ptr<WindowTreeData> window_tree_data_;
+  // List of WindowTreeData structures. When a new window is opened, its data
+  // is appended at the end of that list and it remains uninitialized until the
+  // next call to InitWindowTreeData.
+  std::vector<std::unique_ptr<WindowTreeData>> window_tree_data_list_;
 
   DISALLOW_COPY_AND_ASSIGN(MusDemo);
 };
 
 }  // namespace demo
 }  // namespace ui
 
 #endif  // SERVICES_UI_DEMO_MUS_DEMO_H_