aura-mus: wire up drag and drop.

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"
 #include "base/observer_list.h"
 #include "base/supports_user_data.h"
 #include "ui/aura/aura_export.h"
+#include "ui/base/dragdrop/os_exchange_data_provider_factory.h"
 #include "ui/events/event_handler.h"
 #include "ui/events/event_target.h"
 #include "ui/gfx/geometry/point.h"
 
 namespace ui {
 class ContextFactory;
 class ContextFactoryPrivate;
 class PlatformEventSource;
 }
 namespace aura {
 
 namespace client {
 class FocusClient;
 }
 
 namespace test {
 class EnvTestHelper;
 }
 
 class EnvObserver;
 class InputStateLookup;
 class MusMouseLocationUpdater;
 class Window;
 class WindowPort;
 class WindowTreeClient;
 class WindowTreeHost;
 
 // A singleton object that tracks general state within Aura.
-class AURA_EXPORT Env : public ui::EventTarget, public base::SupportsUserData {
+class AURA_EXPORT Env : public ui::EventTarget,
+                        public ui::OSExchangeDataProviderFactory::Factory,
+                        public base::SupportsUserData {
  public:
   enum class Mode {
     // Classic aura.
     LOCAL,
 
     // Aura with a backend of mus.
     MUS,
   };
 
   ~Env() override;
@@ skipping 78 matching lines @@
   void NotifyHostActivated(WindowTreeHost* host);
 
   void OnActiveFocusClientWindowDestroying();
 
   // 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_;
   WindowTreeClient* window_tree_client_ = nullptr;
 
   base::ObserverList<EnvObserver> observers_;
 
   int mouse_button_flags_;
   // Location of last mouse event, in screen coordinates.
   mutable gfx::Point last_mouse_location_;
@@ skipping 13 matching lines @@
   client::FocusClient* active_focus_client_ = nullptr;
   std::unique_ptr<ActiveFocusClientWindowObserver>
       active_focus_client_window_observer_;
 
   DISALLOW_COPY_AND_ASSIGN(Env);
 };
 
 }  // namespace aura
 
 #endif  // UI_AURA_ENV_H_