Making sure that SpeechRecognitionDispatcherHost is not used after free

content/browser/speech/speech_recognition_dispatcher_host.h

 // 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.
 
 #ifndef CONTENT_BROWSER_SPEECH_SPEECH_RECOGNITION_DISPATCHER_HOST_H_
 #define CONTENT_BROWSER_SPEECH_SPEECH_RECOGNITION_DISPATCHER_HOST_H_
 
 #include "base/memory/scoped_ptr.h"
+#include "base/memory/weak_ptr.h"
 #include "content/common/content_export.h"
 #include "content/public/browser/browser_message_filter.h"
 #include "content/public/browser/speech_recognition_event_listener.h"
 #include "net/url_request/url_request_context_getter.h"
 
 struct SpeechRecognitionHostMsg_StartRequest_Params;
 
 namespace content {
 
 class SpeechRecognitionManager;
 struct SpeechRecognitionResult;
 
 // SpeechRecognitionDispatcherHost is a delegate for Speech API messages used by
 // RenderMessageFilter. Basically it acts as a proxy, relaying the events coming
 // from the SpeechRecognitionManager to IPC messages (and vice versa).
 // It's the complement of SpeechRecognitionDispatcher (owned by RenderView).
 class CONTENT_EXPORT SpeechRecognitionDispatcherHost
     : public BrowserMessageFilter,
       public SpeechRecognitionEventListener {
  public:
   SpeechRecognitionDispatcherHost(
       bool is_guest,
       int render_process_id,
       net::URLRequestContextGetter* context_getter);
 
+  base::WeakPtr<SpeechRecognitionDispatcherHost> AsWeakPtr();
+
   // SpeechRecognitionEventListener methods.
   virtual void OnRecognitionStart(int session_id) OVERRIDE;
   virtual void OnAudioStart(int session_id) OVERRIDE;
   virtual void OnEnvironmentEstimationComplete(int session_id) OVERRIDE;
   virtual void OnSoundStart(int session_id) OVERRIDE;
   virtual void OnSoundEnd(int session_id) OVERRIDE;
   virtual void OnAudioEnd(int session_id) OVERRIDE;
   virtual void OnRecognitionEnd(int session_id) OVERRIDE;
   virtual void OnRecognitionResults(
       int session_id,
       const SpeechRecognitionResults& results) OVERRIDE;
   virtual void OnRecognitionError(
       int session_id,
       const SpeechRecognitionError& error) OVERRIDE;
   virtual void OnAudioLevelsChange(int session_id,
                                    float volume,
                                    float noise_volume) OVERRIDE;
 
   // BrowserMessageFilter implementation.
   virtual bool OnMessageReceived(const IPC::Message& message,
                                  bool* message_was_ok) OVERRIDE;
   virtual void OverrideThreadForMessage(
       const IPC::Message& message,
       BrowserThread::ID* thread) OVERRIDE;
 
+  virtual void OnChannelClosing() OVERRIDE;
+
  private:
   virtual ~SpeechRecognitionDispatcherHost();
 
   void OnStartRequest(
       const SpeechRecognitionHostMsg_StartRequest_Params& params);
   void OnStartRequestOnIO(
       int embedder_render_process_id,
       int embedder_render_view_id,
       const SpeechRecognitionHostMsg_StartRequest_Params& params,
       bool filter_profanities);
   void OnAbortRequest(int render_view_id, int request_id);
   void OnStopCaptureRequest(int render_view_id, int request_id);
 
   bool is_guest_;
   int render_process_id_;
   scoped_refptr<net::URLRequestContextGetter> context_getter_;
 
+  // Used for posting asynchronous tasks (on the IO thread) without worrying
+  // about this class being destroyed in the meanwhile (due to browser shutdown)
+  // since tasks pending on a destroyed WeakPtr are automatically discarded.
+  base::WeakPtrFactory<SpeechRecognitionDispatcherHost> weak_factory_;
+
   DISALLOW_COPY_AND_ASSIGN(SpeechRecognitionDispatcherHost);
 };
 
 }  // namespace content
 
 #endif  // CONTENT_BROWSER_SPEECH_SPEECH_RECOGNITION_DISPATCHER_HOST_H_