Revert EnableClose() removal and related crash fixes. I don't understand the crashes here, and th...

ui/views/widget/widget.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_WIDGET_WIDGET_H_
 #define UI_VIEWS_WIDGET_WIDGET_H_
 #pragma once
 
 #include <set>
 #include <stack>
@@ skipping 303 matching lines @@
 
   // Hides the widget then closes it after a return to the message loop.
   virtual void Close();
 
   // TODO(beng): Move off public API.
   // Closes the widget immediately. Compare to |Close|. This will destroy the
   // window handle associated with this Widget, so should not be called from
   // any code that expects it to be valid beyond this call.
   void CloseNow();
 
+  // Toggles the enable state for the Close button (and the Close menu item in
+  // the system menu).
+  void EnableClose(bool enable);
+
   // Shows or hides the widget, without changing activation state.
   virtual void Show();
   void Hide();
 
   // Like Show(), but does not activate the window.
   void ShowInactive();
 
   // Activates the widget, assuming it already exists and is visible.
   void Activate();
 
@@ skipping 392 matching lines @@
   // duplicate move events even though the mouse hasn't moved.
   bool last_mouse_event_was_move_;
   gfx::Point last_mouse_event_position_;
 
   DISALLOW_COPY_AND_ASSIGN(Widget);
 };
 
 }  // namespace views
 
 #endif  // UI_VIEWS_WIDGET_WIDGET_H_