Stop utterances from a tab when that tab is closed.

chrome/browser/speech/tts_message_filter.h

 // Copyright (c) 2013 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 CHROME_BROWSER_SPEECH_TTS_MESSAGE_FILTER_H_
 #define CHROME_BROWSER_SPEECH_TTS_MESSAGE_FILTER_H_
 
 #include "base/memory/weak_ptr.h"
+#include "base/synchronization/lock.h"
 #include "chrome/browser/speech/tts_controller.h"
 #include "chrome/common/tts_messages.h"
 #include "content/public/browser/browser_message_filter.h"
 
 namespace content {
 class BrowserContext;
 }
 
 class TtsMessageFilter
     : public content::BrowserMessageFilter,
@@ skipping 26 matching lines @@
   ~TtsMessageFilter() override;
 
   void OnInitializeVoiceList();
   void OnSpeak(const TtsUtteranceRequest& utterance);
   void OnPause();
   void OnResume();
   void OnCancel();
 
   void OnChannelClosingInUIThread();
 
+  void Cleanup();
+
+  // Thread-safe check to make sure this class is still valid and not
+  // about to be deleted.
+  bool Valid();
+
   int render_process_id_;
   content::BrowserContext* browser_context_;
-
-  base::WeakPtrFactory<TtsMessageFilter> weak_ptr_factory_;
+  mutable base::Lock mutex_;
+  mutable bool valid_;
 
   DISALLOW_COPY_AND_ASSIGN(TtsMessageFilter);
 };
 
 #endif  // CHROME_BROWSER_SPEECH_TTS_MESSAGE_FILTER_H_