Adds a porting layer so aura can be made to work with mus

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/callback.h"
 #include "base/macros.h"
 #include "base/observer_list.h"
 #include "base/supports_user_data.h"
 #include "ui/aura/aura_export.h"
 #include "ui/events/event_handler.h"
 #include "ui/events/event_target.h"
 #include "ui/gfx/geometry/point.h"
 
 namespace ui {
 class ContextFactory;
 class PlatformEventSource;
 }
 namespace aura {
 
 namespace test {
 class EnvTestHelper;
 }
 
 class EnvObserver;
 class InputStateLookup;
 class Window;
+class WindowPort;
 class WindowTreeHost;
 
 // A singleton object that tracks general state within Aura.
 class AURA_EXPORT Env : public ui::EventTarget, public base::SupportsUserData {
  public:
   ~Env() override;
 
-  static std::unique_ptr<Env> CreateInstance();
+  using WindowPortFactory =
+      base::Callback<std::unique_ptr<WindowPort>(Window* window)>;
+  static std::unique_ptr<Env> CreateInstance(
+      const WindowPortFactory& window_port_factory = WindowPortFactory());
   static Env* GetInstance();
   static Env* GetInstanceDontCreate();
 
+  // Called internally to create the appropriate WindowPort implementation.
+  std::unique_ptr<WindowPort> CreateWindowPort(Window* window);
+
   void AddObserver(EnvObserver* observer);
   void RemoveObserver(EnvObserver* observer);
 
   int mouse_button_flags() const { return mouse_button_flags_; }
   void set_mouse_button_flags(int mouse_button_flags) {
     mouse_button_flags_ = mouse_button_flags;
   }
   // Returns true if a mouse button is down. This may query the native OS,
   // otherwise it uses |mouse_button_flags_|.
   bool IsMouseButtonDown() const;
@@ skipping 12 matching lines @@
   void set_context_factory(ui::ContextFactory* context_factory) {
     context_factory_ = context_factory;
   }
   ui::ContextFactory* context_factory() { return context_factory_; }
 
  private:
   friend class test::EnvTestHelper;
   friend class Window;
   friend class WindowTreeHost;
 
-  Env();
+  explicit Env(const WindowPortFactory& window_port_factory);
 
   void Init();
 
   // 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);
 
   // 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;
 
+  WindowPortFactory window_port_factory_;
+
   base::ObserverList<EnvObserver> observers_;
 
   int mouse_button_flags_;
   // Location of last mouse event, in screen coordinates.
   gfx::Point last_mouse_location_;
   bool is_touch_down_;
 
   std::unique_ptr<InputStateLookup> input_state_lookup_;
   std::unique_ptr<ui::PlatformEventSource> event_source_;
 
   ui::ContextFactory* context_factory_;
 
   DISALLOW_COPY_AND_ASSIGN(Env);
 };
 
 }  // namespace aura
 
 #endif  // UI_AURA_ENV_H_