First shot at implementing drag&drop for Aura

ui/aura/desktop.h

 // Copyright (c) 2011 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_DESKTOP_H_
 #define UI_AURA_DESKTOP_H_
 #pragma once
 
 #include "base/basictypes.h"
 #include "base/memory/ref_counted.h"
 #include "base/memory/weak_ptr.h"
 #include "base/message_loop.h"
 #include "base/task.h"
 #include "ui/aura/aura_export.h"
 #include "ui/aura/cursor.h"
 #include "ui/aura/focus_manager.h"
 #include "ui/aura/window.h"
+#include "ui/base/dragdrop/os_exchange_data.h"
 #include "ui/base/events.h"
 #include "ui/gfx/compositor/compositor.h"
 #include "ui/gfx/compositor/layer_animation_observer.h"
 #include "ui/gfx/native_widget_types.h"
 #include "ui/gfx/point.h"
 
 namespace gfx {
 class Size;
 }
 
@@ skipping 96 matching lines @@
 
   // Sets capture to the specified window.
   void SetCapture(Window* window);
 
   // If |window| has mouse capture, the current capture window is set to NULL.
   void ReleaseCapture(Window* window);
 
   // Overridden from Window:
   virtual void SetTransform(const ui::Transform& transform) OVERRIDE;
 
+  // Initiates a drag and drop session
+  virtual void StartDragAndDrop(const ui::OSExchangeData& data, int operation);
+
  private:
   // Called whenever the mouse moves, tracks the current |mouse_moved_handler_|,
   // sending exited and entered events as its value changes.
   void HandleMouseMoved(const MouseEvent& event, Window* target);
 
   bool ProcessMouseEvent(Window* target, MouseEvent* event);
   bool ProcessKeyEvent(Window* target, KeyEvent* event);
   ui::TouchStatus ProcessTouchEvent(Window* target, TouchEvent* event);
 
   // Overridden from ui::CompositorDelegate
@@ skipping 55 matching lines @@
 
   // The capture window. When not-null, this window receives all the mouse and
   // touch events.
   Window* capture_window_;
 
   Window* mouse_pressed_handler_;
   Window* mouse_moved_handler_;
   Window* focused_window_;
   Window* touch_event_handler_;
 
+  bool drag_drop_in_progress_;
+
   DISALLOW_COPY_AND_ASSIGN(Desktop);
 };
 
 }  // namespace aura
 
 #endif  // UI_AURA_DESKTOP_H_