We have a problem in the process on destroying WebContentsImpl because

chrome/browser/ui/website_settings/permission_bubble_manager.cc

 // Copyright 2014 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/website_settings/permission_bubble_manager.h"
 
 #include "base/command_line.h"
 #include "base/metrics/user_metrics_action.h"
 #include "chrome/browser/ui/website_settings/permission_bubble_request.h"
 #include "chrome/common/chrome_switches.h"
@@ skipping 216 matching lines @@
     return;
 
   // If we have navigated to a new url...
   if (request_url_ != web_contents()->GetLastCommittedURL()) {
     // Kill off existing bubble and cancel any pending requests.
     CancelPendingQueue();
     FinalizeBubble();
   }
 }
 
-void PermissionBubbleManager::WebContentsDestroyed(
-    content::WebContents* web_contents) {
+void PermissionBubbleManager::WebContentsDestroyed() {
   // If the web contents has been destroyed, treat the bubble as cancelled.
   CancelPendingQueue();
   FinalizeBubble();
 
   // The WebContents is going away; be aggressively paranoid and delete
   // ourselves lest other parts of the system attempt to add permission bubbles
   // or use us otherwise during the destruction.
-  web_contents->RemoveUserData(UserDataKey());
+  web_contents()->RemoveUserData(UserDataKey());
   // That was the equivalent of "delete this". This object is now destroyed;
   // returning from this function is the only safe thing to do.
 }
 
 void PermissionBubbleManager::ToggleAccept(int request_index, bool new_value) {
   DCHECK(request_index < static_cast<int>(accept_states_.size()));
   accept_states_[request_index] = new_value;
 }
 
 void PermissionBubbleManager::SetCustomizationMode() {
@@ skipping 77 matching lines @@
 }
 
 void PermissionBubbleManager::CancelPendingQueue() {
   std::vector<PermissionBubbleRequest*>::iterator requests_iter;
   for (requests_iter = queued_requests_.begin();
        requests_iter != queued_requests_.end();
        requests_iter++) {
     (*requests_iter)->RequestFinished();
   }
 }