It is time.

ui/wm/public/drag_drop_delegate.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_WM_PUBLIC_DRAG_DROP_DELEGATE_H_
-#define UI_WM_PUBLIC_DRAG_DROP_DELEGATE_H_
-
-#include "ui/aura/aura_export.h"
-
-namespace ui {
-class DropTargetEvent;
-}
-
-namespace aura {
-class Window;
-namespace client {
-
-// Delegate interface for drag and drop actions on aura::Window.
-class AURA_EXPORT DragDropDelegate {
- public:
-  // OnDragEntered is invoked when the mouse enters this window during a drag &
-  // drop session. This is immediately followed by an invocation of
-  // OnDragUpdated, and eventually one of OnDragExited or OnPerformDrop.
-  virtual void OnDragEntered(const ui::DropTargetEvent& event) = 0;
-
-  // Invoked during a drag and drop session while the mouse is over the window.
-  // This should return a bitmask of the DragDropTypes::DragOperation supported
-  // based on the location of the event. Return 0 to indicate the drop should
-  // not be accepted.
-  virtual int OnDragUpdated(const ui::DropTargetEvent& event) = 0;
-
-  // Invoked during a drag and drop session when the mouse exits the window, or
-  // when the drag session was canceled and the mouse was over the window.
-  virtual void OnDragExited() = 0;
-
-  // Invoked during a drag and drop session when OnDragUpdated returns a valid
-  // operation and the user release the mouse.
-  virtual int OnPerformDrop(const ui::DropTargetEvent& event) = 0;
-
- protected:
-  virtual ~DragDropDelegate() {}
-};
-
-AURA_EXPORT void SetDragDropDelegate(Window* window,
-                                     DragDropDelegate* delegate);
-AURA_EXPORT DragDropDelegate* GetDragDropDelegate(Window* window);
-
-}  // namespace client
-}  // namespace aura
-
-#endif  // UI_WM_PUBLIC_DRAG_DROP_DELEGATE_H_