Uses a system-wide notion of isSpeaking in the Mac extension TTS api.

chrome/browser/speech/extension_api/tts_extension_api_chromeos.cc

 // 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.
 
 #include "chrome/browser/speech/extension_api/tts_extension_api_chromeos.h"
 
 #include <list>
 
 #include "base/bind.h"
 #include "base/memory/singleton.h"
@@ skipping 29 matching lines @@
   }
 
   virtual bool Speak(
       int utterance_id,
       const std::string& utterance,
       const std::string& lang,
       const UtteranceContinuousParameters& params);
 
   virtual bool StopSpeaking();
 
+  virtual bool IsSpeaking();
+
   virtual bool SendsEvent(TtsEventType event_type);
 
   // Get the single instance of this class.
   static ExtensionTtsPlatformImplChromeOs* GetInstance();
 
   // TTS won't begin until this is called.
   void Enable();
 
  private:
   ExtensionTtsPlatformImplChromeOs();
@@ skipping 96 matching lines @@
   if (!enabled_) {
     STLDeleteElements(&queued_utterances_);
     return true;
   }
 
   chromeos::DBusThreadManager::Get()->GetSpeechSynthesizerClient()->
       StopSpeaking();
   return true;
 }
 
+bool ExtensionTtsPlatformImplChromeOs::IsSpeaking() {
+  // Defers to controller's utterance based detection of is speaking.
+  return true;
+}
+
 bool ExtensionTtsPlatformImplChromeOs::SendsEvent(TtsEventType event_type) {
   return (event_type == TTS_EVENT_START ||
           event_type == TTS_EVENT_END ||
           event_type == TTS_EVENT_ERROR);
 }
 
 void ExtensionTtsPlatformImplChromeOs::Enable() {
   enabled_ = true;
   while (!queued_utterances_.empty()) {
     QueuedUtterance* queued = queued_utterances_.front();
@@ skipping 54 matching lines @@
 // static
 ExtensionTtsPlatformImplChromeOs*
 ExtensionTtsPlatformImplChromeOs::GetInstance() {
   return Singleton<ExtensionTtsPlatformImplChromeOs>::get();
 }
 
 // global
 void EnableChromeOsTts() {
   ExtensionTtsPlatformImplChromeOs::GetInstance()->Enable();
 }