Refactor TouchSelectionDraggableClient APIs

ui/touch_selection/touch_selection_draggable.h

 // Copyright 2015 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_TOUCH_SELECTION_DRAG_DRAGGABLE_H_
 #define UI_TOUCH_SELECTION_DRAG_DRAGGABLE_H_
 
 #include "ui/gfx/geometry/point_f.h"
 #include "ui/touch_selection/ui_touch_selection_export.h"
 
 namespace ui {
 
 class MotionEvent;
 class TouchSelectionDraggable;
 
+enum TouchHandleDragEvent {
+  HANDLE_DRAG_BEGIN,
+  HANDLE_DRAG_UPDATE,
+  HANDLE_DRAG_END
+};
+
 // Interface through which TouchSelectionDraggable manipulates the selection.
 class UI_TOUCH_SELECTION_EXPORT TouchSelectionDraggableClient {
  public:
   virtual ~TouchSelectionDraggableClient() {}
-  virtual void OnDragBegin(const TouchSelectionDraggable& draggable,
+  virtual void OnDragEvent(const TouchHandleDragEvent event,
+                           const TouchSelectionDraggable& draggable,
                            const gfx::PointF& start_position) = 0;
-  virtual void OnDragUpdate(const TouchSelectionDraggable& draggable,
-                            const gfx::PointF& new_position) = 0;
-  virtual void OnDragEnd(const TouchSelectionDraggable& draggable) = 0;
   virtual bool IsWithinTapSlop(const gfx::Vector2dF& delta) const = 0;
 };
 
 // Generic interface for entities that manipulate the selection via dragging.
 class UI_TOUCH_SELECTION_EXPORT TouchSelectionDraggable {
  protected:
   virtual ~TouchSelectionDraggable() {}
 
   // Offers a touch sequence to the draggable target. Returns true if the event
   // was consumed, in which case the caller should cease further handling.
   virtual bool WillHandleTouchEvent(const ui::MotionEvent& event) = 0;
 
   // Whether a drag is active OR being detected for the current touch sequence.
   virtual bool IsActive() const = 0;
 };
 
 }  // namespace ui
 
 #endif  // UI_TOUCH_SELECTION_DRAG_DRAGGABLE_H_