Use a weak pointer to determine if resizer was destroyed by nested Drag calls.

ash/wm/panels/panel_window_resizer.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 ASH_WM_PANELS_PANEL_WINDOW_RESIZER_H_
 #define ASH_WM_PANELS_PANEL_WINDOW_RESIZER_H_
 
 #include "ash/wm/window_resizer.h"
 #include "base/compiler_specific.h"
+#include "base/memory/weak_ptr.h"
 
 namespace gfx {
 class Rect;
 class Point;
 }
 
 namespace ash {
 
 // PanelWindowResizer is used by ToplevelWindowEventFilter to handle dragging,
 // moving or resizing panel window. These can be attached and detached from the
@@ skipping 56 matching lines @@
 
   // Set to true once Drag() is invoked and the bounds of the window change.
   bool did_move_or_resize_;
 
   // True if the window started attached to the launcher.
   const bool was_attached_;
 
   // True if the window should attach to the launcher after releasing.
   bool should_attach_;
 
-  // If non-NULL the destructor sets this to true. Used to determine if this has
-  // been deleted.
-  bool* destroyed_;
+  base::WeakPtrFactory<PanelWindowResizer> weak_ptr_factory_;
 
   DISALLOW_COPY_AND_ASSIGN(PanelWindowResizer);
 };
 
 }  // namespace ash
 
 #endif  // ASH_WM_PANELS_PANEL_WINDOW_RESIZER_H_