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

ash/wm/drag_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_DRAG_WINDOW_RESIZER_H_
 #define ASH_WM_DRAG_WINDOW_RESIZER_H_
 
 #include "ash/wm/window_resizer.h"
 #include "base/compiler_specific.h"
 #include "base/gtest_prod_util.h"
+#include "base/memory/weak_ptr.h"
 #include "ui/gfx/point.h"
 
 namespace ash {
 namespace internal {
 
 class DragWindowController;
 
 // DragWindowResizer is a decorator of WindowResizer and adds the ability to
 // drag windows across displays.
 class ASH_EXPORT DragWindowResizer : public WindowResizer {
@@ skipping 34 matching lines @@
 
   scoped_ptr<WindowResizer> next_window_resizer_;
 
   // Shows a semi-transparent image of the window being dragged.
   scoped_ptr<DragWindowController> drag_window_controller_;
 
   const Details details_;
 
   gfx::Point last_mouse_location_;
 
-  // If non-NULL the destructor sets this to true. Used to determine if this has
-  // been deleted.
-  bool* destroyed_;
-
   // Current instance for use by the DragWindowResizerTest.
   static DragWindowResizer* instance_;
 
+  base::WeakPtrFactory<DragWindowResizer> weak_ptr_factory_;
+
   DISALLOW_COPY_AND_ASSIGN(DragWindowResizer);
 };
 
 }  // namespace internal
 }  // namespace aura
 
 #endif  // ASH_WM_DRAG_WINDOW_RESIZER_H_