mash: Avoid shelf crashes on display removal.

ash/mus/window_manager.h

 // Copyright 2015 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 ASH_MUS_WINDOW_MANAGER_H_
 #define ASH_MUS_WINDOW_MANAGER_H_
 
 #include <stdint.h>
 
 #include <memory>
 #include <set>
 
 #include "base/macros.h"
 #include "base/observer_list.h"
+#include "mojo/public/cpp/bindings/binding.h"
 #include "services/ui/common/types.h"
 #include "services/ui/public/cpp/window_manager_delegate.h"
 #include "services/ui/public/cpp/window_observer.h"
 #include "services/ui/public/cpp/window_tree_client_delegate.h"
+#include "services/ui/public/interfaces/display.mojom.h"
 #include "services/ui/public/interfaces/window_manager.mojom.h"
 
 namespace display {
 class Display;
-class Screen;
+class ScreenBase;
 }
 
 namespace shell {
 class Connector;
 }
 
 namespace views {
 class PointerWatcherEventRouter;
 }
 
 namespace ash {
 namespace mus {
 
 class AcceleratorHandler;
 class RootWindowController;
 class ShadowController;
 class WindowManagerObserver;
 class WmShellMus;
 class WmLookupMus;
 class WmTestHelper;
 
 // WindowManager serves as the WindowManagerDelegate and
 // WindowTreeClientDelegate for mash. WindowManager creates (and owns)
 // a RootWindowController per Display. WindowManager takes ownership of
 // the WindowTreeClient.
 class WindowManager : public ui::WindowManagerDelegate,
                       public ui::WindowObserver,
-                      public ui::WindowTreeClientDelegate {
+                      public ui::WindowTreeClientDelegate,
+                      public ui::mojom::DisplayManagerObserver {
  public:
   explicit WindowManager(shell::Connector* connector);
   ~WindowManager() override;
 
   void Init(ui::WindowTreeClient* window_tree_client);
 
   WmShellMus* shell() { return shell_.get(); }
 
   ui::WindowTreeClient* window_tree_client() { return window_tree_client_; }
 
@@ skipping 52 matching lines @@
   void OnWmNewDisplay(ui::Window* window,
                       const display::Display& display) override;
   void OnWmPerformMoveLoop(ui::Window* window,
                            ui::mojom::MoveLoopSource source,
                            const gfx::Point& cursor_location,
                            const base::Callback<void(bool)>& on_done) override;
   void OnWmCancelMoveLoop(ui::Window* window) override;
   ui::mojom::EventResult OnAccelerator(uint32_t id,
                                        const ui::Event& event) override;
 
+  // ui::mojom::DisplayManager:
+  void OnDisplays(mojo::Array<ui::mojom::WsDisplayPtr> ws_displays) override;
+  void OnDisplaysChanged(
+      mojo::Array<ui::mojom::WsDisplayPtr> ws_displays) override;
+  void OnDisplayRemoved(int64_t id) override;
+
   shell::Connector* connector_;
 
   ui::WindowTreeClient* window_tree_client_ = nullptr;
 
   ui::WindowManagerClient* window_manager_client_ = nullptr;
 
   std::unique_ptr<views::PointerWatcherEventRouter>
       pointer_watcher_event_router_;
 
   std::unique_ptr<ShadowController> shadow_controller_;
 
   std::set<std::unique_ptr<RootWindowController>> root_window_controllers_;
 
   base::ObserverList<WindowManagerObserver> observers_;
 
-  std::unique_ptr<display::Screen> screen_;
+  std::unique_ptr<display::ScreenBase> screen_;
+  mojo::Binding<ui::mojom::DisplayManagerObserver>
+      display_manager_observer_binding_;
 
   std::unique_ptr<WmShellMus> shell_;
 
   std::unique_ptr<WmLookupMus> lookup_;
 
   std::map<uint16_t, AcceleratorHandler*> accelerator_handlers_;
   uint16_t next_accelerator_namespace_id_ = 0u;
 
   DISALLOW_COPY_AND_ASSIGN(WindowManager);
 };
 
 }  // namespace mus
 }  // namespace ash
 
 #endif  // ASH_MUS_WINDOW_MANAGER_H_