It is time.

ui/views/drag_controller.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_VIEWS_DRAG_CONTROLLER_H_
-#define UI_VIEWS_DRAG_CONTROLLER_H_
-
-#include "ui/views/views_export.h"
-
-namespace gfx {
-class Point;
-}
-
-namespace ui {
-class OSExchangeData;
-}
-
-namespace views {
-class View;
-
-// DragController is responsible for writing drag data for a view, as well as
-// supplying the supported drag operations. Use DragController if you don't
-// want to subclass.
-class VIEWS_EXPORT DragController {
- public:
-  // Writes the data for the drag.
-  virtual void WriteDragDataForView(View* sender,
-                                    const gfx::Point& press_pt,
-                                    ui::OSExchangeData* data) = 0;
-
-  // Returns the supported drag operations (see DragDropTypes for possible
-  // values). A drag is only started if this returns a non-zero value.
-  virtual int GetDragOperationsForView(View* sender,
-                                       const gfx::Point& p) = 0;
-
-  // Returns true if a drag operation can be started.
-  // |press_pt| represents the coordinates where the mouse was initially
-  // pressed down. |p| is the current mouse coordinates.
-  virtual bool CanStartDragForView(View* sender,
-                                   const gfx::Point& press_pt,
-                                   const gfx::Point& p) = 0;
-
- protected:
-  virtual ~DragController() {}
-};
-
-}  // namespace views
-
-#endif  // UI_VIEWS_DRAG_CONTROLLER_H_