Support dragging panels to stack and snap.

chrome/browser/ui/panels/stacked_panel_drag_handler.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 CHROME_BROWSER_UI_PANELS_STACKED_PANEL_DRAG_HANDLER_H_
 #define CHROME_BROWSER_UI_PANELS_STACKED_PANEL_DRAG_HANDLER_H_
 
 #include "base/basictypes.h"
 
 class Panel;
 namespace gfx {
 class Point;
 }
 
 // Handles all the drags to unstacked free-floating panels.
 class StackedPanelDragHandler {
  public:
-  static void HandleDrag(Panel* panel, const gfx::Point& target_position);
+  static void HandleDrag(Panel* panel,
+                         const gfx::Point& target_position,
+                         bool in_orginal_collection);
+
+  static void FinalizeDrag(Panel* panel);
 
  private:
   DISALLOW_IMPLICIT_CONSTRUCTORS(StackedPanelDragHandler);
 };
 
 #endif  // CHROME_BROWSER_UI_PANELS_STACKED_PANEL_DRAG_HANDLER_H_