extensions: Destroy ExtensionMessageFilter on IO thread.

extensions/browser/extension_message_filter.h

 // 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.
 
 #ifndef EXTENSIONS_BROWSER_EXTENSION_MESSAGE_FILTER_H_
 #define EXTENSIONS_BROWSER_EXTENSION_MESSAGE_FILTER_H_
 
 #include <string>
 #include <vector>
 
@@ skipping 20 matching lines @@
 // renderer process. It is created on the UI thread. Messages may be handled on
 // the IO thread or the UI thread.
 class ExtensionMessageFilter : public content::BrowserMessageFilter {
  public:
   ExtensionMessageFilter(int render_process_id,
                          content::BrowserContext* context);
 
   int render_process_id() { return render_process_id_; }
 
  private:
+  friend class content::BrowserThread;
+  friend class base::DeleteHelper<ExtensionMessageFilter>;
+
   virtual ~ExtensionMessageFilter();
 
   // content::BrowserMessageFilter implementation.
   virtual void OverrideThreadForMessage(
       const IPC::Message& message,
       content::BrowserThread::ID* thread) OVERRIDE;
+  virtual void OnDestruct() const OVERRIDE;
   virtual bool OnMessageReceived(const IPC::Message& message) OVERRIDE;
 
   // Message handlers on the UI thread.
   void OnExtensionAddListener(const std::string& extension_id,
                               const std::string& event_name);
   void OnExtensionRemoveListener(const std::string& extension_id,
                                  const std::string& event_name);
   void OnExtensionAddLazyListener(const std::string& extension_id,
                                   const std::string& event_name);
   void OnExtensionRemoveLazyListener(const std::string& extension_id,
@@ skipping 18 matching lines @@
       int routing_id,
       const ExtensionHostMsg_Request_Params& params);
 
   const int render_process_id_;
 
   // Should only be accessed on the UI thread.
   content::BrowserContext* browser_context_;
 
   scoped_refptr<extensions::InfoMap> extension_info_map_;
 
+  // Weak pointers produced by this factory are bound to the IO thread.
   base::WeakPtrFactory<ExtensionMessageFilter> weak_ptr_factory_;
 
   DISALLOW_COPY_AND_ASSIGN(ExtensionMessageFilter);
 };
 
 }  // namespace extensions
 
 #endif  // EXTENSIONS_BROWSER_EXTENSION_MESSAGE_FILTER_H_