Cleanup: remove redundant tab close observation from TabModalConfirmDialogDelegate

chrome/browser/ui/gtk/tab_modal_confirm_dialog_gtk.cc

 // 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.
 
 #include "chrome/browser/ui/gtk/tab_modal_confirm_dialog_gtk.h"
 
 #include "base/message_loop/message_loop.h"
 #include "base/strings/utf_string_conversions.h"
 #include "chrome/browser/profiles/profile.h"
 #include "chrome/browser/ui/browser.h"
@@ skipping 91 matching lines @@
 
   window_ = CreateWebContentsModalDialogGtk(dialog_, cancel_);
   delegate_->set_operations_delegate(this);
 
   WebContentsModalDialogManager* web_contents_modal_dialog_manager =
       WebContentsModalDialogManager::FromWebContents(web_contents);
   web_contents_modal_dialog_manager->ShowDialog(window_);
 }
 
 TabModalConfirmDialogGtk::~TabModalConfirmDialogGtk() {
+  // Provide a disposition in case the dialog was closed without accepting or
+  // cancelling.
+  delegate_->Cancel();
+
   gtk_widget_destroy(dialog_);
 }
 
 void TabModalConfirmDialogGtk::AcceptTabModalDialog() {
   OnAccept(NULL);
 }
 
 void TabModalConfirmDialogGtk::CancelTabModalDialog() {
   OnCancel(NULL);
 }
@@ skipping 17 matching lines @@
   delegate_->Cancel();
 }
 
 void TabModalConfirmDialogGtk::OnLinkClicked(GtkWidget* widget) {
   delegate_->LinkClicked(event_utils::DispositionForCurrentButtonPressEvent());
 }
 
 void TabModalConfirmDialogGtk::OnDestroy(GtkWidget* widget) {
   delete this;
 }