We have a problem in the process on destroying WebContentsImpl because

chrome/browser/ui/cocoa/hung_renderer_controller.mm

 // 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.
 
 #import "chrome/browser/ui/cocoa/hung_renderer_controller.h"
 
 #import <Cocoa/Cocoa.h>
 
 #include "base/mac/bundle_locations.h"
 #include "base/mac/mac_util.h"
@@ skipping 33 matching lines @@
                             HungRendererController* controller)
     : content::WebContentsObserver(web_contents),
       controller_(controller) {
   }
 
  protected:
   // WebContentsObserver overrides:
   virtual void RenderProcessGone(base::TerminationStatus status) OVERRIDE {
     [controller_ renderProcessGone];
   }
-  virtual void WebContentsDestroyed(WebContents* tab) OVERRIDE {
+  virtual void WebContentsDestroyed() OVERRIDE {
     [controller_ renderProcessGone];
   }
 
  private:
   HungRendererController* controller_;  // weak
 
   DISALLOW_COPY_AND_ASSIGN(WebContentsObserverBridge);
 };
 
 @implementation HungRendererController
@@ skipping 166 matching lines @@
     [g_instance showForWebContents:contents];
   }
 }
 
 void HideHungRendererDialog(WebContents* contents) {
   if (!logging::DialogsAreSuppressed() && g_instance)
     [g_instance endForWebContents:contents];
 }
 
 }  // namespace chrome