chromeos: makes it possible for windows to outlive WindowTreeClient

ui/aura/env.h

 // Copyright (c) 2012 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 UI_AURA_ENV_H_
 #define UI_AURA_ENV_H_
 
 #include <memory>
 
 #include "base/macros.h"
@@ skipping 99 matching lines @@
 
   // See CreateInstance() for description.
   void SetWindowTreeClient(WindowTreeClient* window_tree_client);
   bool HasWindowTreeClient() const { return window_tree_client_ != nullptr; }
 
  private:
   friend class test::EnvTestHelper;
   friend class EventInjector;
   friend class MusMouseLocationUpdater;
   friend class Window;
+  friend class WindowTreeClient;  // For call to WindowTreeClientDestroyed().
   friend class WindowTreeHost;
 
   explicit Env(Mode mode);
 
   void Init();
 
   // After calling this method, all OSExchangeDataProvider instances will be
   // Mus instances. We can't do this work in Init(), because our mode may
   // changed via the EnvTestHelper.
   void EnableMusOSExchangeDataProvider();
 
   // Called by the Window when it is initialized. Notifies observers.
   void NotifyWindowInitialized(Window* window);
 
   // Called by the WindowTreeHost when it is initialized. Notifies observers.
   void NotifyHostInitialized(WindowTreeHost* host);
 
   // Invoked by WindowTreeHost when it is activated. Notifies observers.
   void NotifyHostActivated(WindowTreeHost* host);
 
+  void WindowTreeClientDestroyed(WindowTreeClient* client);
+
   // Overridden from ui::EventTarget:
   bool CanAcceptEvent(const ui::Event& event) override;
   ui::EventTarget* GetParentTarget() override;
   std::unique_ptr<ui::EventTargetIterator> GetChildIterator() const override;
   ui::EventTargeter* GetEventTargeter() override;
 
   // Overridden from ui::OSExchangeDataProviderFactory::Factory:
   std::unique_ptr<ui::OSExchangeData::Provider> BuildProvider() override;
 
   // This is not const for tests, which may share Env across tests and so needs
   // to reset the value.
   Mode mode_;
 
   // Intentionally not exposed publicly. Someday we might want to support
-  // multiple WindowTreeClients. Use EnvTestHelper in tests.
+  // multiple WindowTreeClients. Use EnvTestHelper in tests. This is set to null
+  // during shutdown.
   WindowTreeClient* window_tree_client_ = nullptr;
 
   base::ObserverList<EnvObserver> observers_;
 
   std::unique_ptr<EnvInputStateController> env_controller_;
   int mouse_button_flags_;
   // Location of last mouse event, in screen coordinates.
   mutable gfx::Point last_mouse_location_;
   bool is_touch_down_;
   bool get_last_mouse_location_from_mus_;
   // This may be set to true in tests to force using |last_mouse_location_|
   // rather than querying WindowTreeClient.
   bool always_use_last_mouse_location_ = false;
   // Whether we set ourselves as the OSExchangeDataProviderFactory.
   bool is_os_exchange_data_provider_factory_ = false;
 
   std::unique_ptr<InputStateLookup> input_state_lookup_;
   std::unique_ptr<ui::PlatformEventSource> event_source_;
 
 #if defined(USE_OZONE)
   // Factory for pixmaps that can use be transported from the client to the GPU
   // process using a low-level ozone-provided platform specific mechanism.
   std::unique_ptr<gfx::ClientNativePixmapFactory> native_pixmap_factory_;
 #endif
 
   ui::ContextFactory* context_factory_;
   ui::ContextFactoryPrivate* context_factory_private_;
 
+  // This is set to true when the WindowTreeClient is destroyed. It triggers
+  // creating a different WindowPort implementation.
+  bool in_mus_shutdown_ = false;
+
   DISALLOW_COPY_AND_ASSIGN(Env);
 };
 
 }  // namespace aura
 
 #endif  // UI_AURA_ENV_H_