Remove DialogDelegate::OnClosed() which is redundant with

ui/views/window/dialog_client_view.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 UI_VIEWS_WINDOW_DIALOG_CLIENT_VIEW_H_
 #define UI_VIEWS_WINDOW_DIALOG_CLIENT_VIEW_H_
 
 #include "base/gtest_prod_util.h"
 #include "base/macros.h"
 #include "ui/base/ui_base_types.h"
@@ skipping 88 matching lines @@
   // The dialog buttons.
   LabelButton* ok_button_;
   LabelButton* cancel_button_;
 
   // The extra view shown in the row of buttons; may be NULL.
   View* extra_view_;
 
   // The footnote view shown below the buttons; may be NULL.
   View* footnote_view_;
 
-  // True if we've notified the delegate the window is closing and the delegate
-  // allosed the close. In some situations it's possible to get two closes (see
-  // http://crbug.com/71940). This is used to avoid notifying the delegate
-  // twice, which can have bad consequences.
-  bool notified_delegate_;

[sky, 2016/02/11 22:56:56]

Why is this no longer necessary?

-
   DISALLOW_COPY_AND_ASSIGN(DialogClientView);
 };
 
 }  // namespace views
 
 #endif  // UI_VIEWS_WINDOW_DIALOG_CLIENT_VIEW_H_