We have a problem in the process on destroying WebContentsImpl because

components/web_modal/web_contents_modal_dialog_manager.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 "components/web_modal/web_contents_modal_dialog_manager.h"
 
 #include "components/web_modal/web_contents_modal_dialog_manager_delegate.h"
 #include "content/public/browser/navigation_details.h"
 #include "content/public/browser/navigation_entry.h"
 #include "content/public/browser/render_view_host.h"
@@ skipping 170 matching lines @@
 void WebContentsModalDialogManager::WasShown() {
   if (!child_dialogs_.empty())
     child_dialogs_.front()->manager->Show();
 }
 
 void WebContentsModalDialogManager::WasHidden() {
   if (!child_dialogs_.empty())
     child_dialogs_.front()->manager->Hide();
 }
 
-void WebContentsModalDialogManager::WebContentsDestroyed(WebContents* tab) {
+void WebContentsModalDialogManager::WebContentsDestroyed() {
   // First cleanly close all child dialogs.
   // TODO(mpcomplete): handle case if MaybeCloseChildWindows() already asked
   // some of these to close.  CloseAllDialogs is async, so it might get called
   // twice before it runs.
   CloseAllDialogs();
 }
 
 void WebContentsModalDialogManager::DidAttachInterstitialPage() {
   // Copy the dialogs so we can close and remove them while iterating over the
   // list.
   WebContentsModalDialogList dialogs(child_dialogs_);
   for (WebContentsModalDialogList::iterator it = dialogs.begin();
        it != dialogs.end(); ++it) {
     if ((*it)->close_on_interstitial_webui)
       (*it)->manager->Close();
   }
 }
 
 }  // namespace web_modal