Add a basic task switcher to the simple window manager.

mash/simple_wm/simple_wm.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 MASH_SIMPLE_WM_SIMPLE_WM_H_
 #define MASH_SIMPLE_WM_SIMPLE_WM_H_
 
 #include <memory>
 #include <utility>
 
@@ skipping 29 matching lines @@
 namespace simple_wm {
 
 class SimpleWM : public service_manager::Service,
                  public aura::WindowTreeClientDelegate,
                  public aura::WindowManagerDelegate {
  public:
   SimpleWM();
   ~SimpleWM() override;
 
  private:
+  class DisplayLayoutManager;
   class FrameView;
+  class WindowListModel;
+  class WindowListModelObserver;
+  class WindowListView;
 
   // 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 OnLostConnection(aura::WindowTreeClient* client) override;
@@ skipping 25 matching lines @@
                            const gfx::Point& cursor_location,
                            const base::Callback<void(bool)>& on_done) override;
   void OnWmCancelMoveLoop(aura::Window* window) override;
   void OnWmSetClientArea(
       aura::Window* window,
       const gfx::Insets& insets,
       const std::vector<gfx::Rect>& additional_client_areas) override;
 
   FrameView* GetFrameViewForClientWindow(aura::Window* client_window);
 
+  void OnWindowListViewItemActivated(aura::Window* index);
+
   std::unique_ptr<views::AuraInit> aura_init_;
   ::wm::WMState wm_state_;
   std::unique_ptr<display::ScreenBase> screen_;
   aura::PropertyConverter property_converter_;
   aura::test::TestFocusClient focus_client_;
   std::unique_ptr<aura::WindowTreeHostMus> window_tree_host_;
-  aura::Window* root_ = nullptr;
+  aura::Window* display_root_ = nullptr;
+  aura::Window* window_root_ = nullptr;
   aura::WindowManagerClient* window_manager_client_ = nullptr;
   std::unique_ptr<aura::WindowTreeClient> window_tree_client_;
   std::unique_ptr<ui::GpuService> gpu_service_;
   std::unique_ptr<aura::MusContextFactory> compositor_context_factory_;
   std::map<aura::Window*, FrameView*> client_window_to_frame_view_;
+  std::unique_ptr<WindowListModel> window_list_model_;
 
   bool started_ = false;
 
   DISALLOW_COPY_AND_ASSIGN(SimpleWM);
 };
 
 }  // namespace simple_wm
 
 #endif  // MASH_SIMPLE_WM_SIMPLE_WM_H_