An improved fix for TTS Extension API problems on Windows.

chrome/browser/extensions/extension_tts_api_win.cc

 // Copyright (c) 2011 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 <math.h>
 #include <sapi.h>
 
 #include "base/memory/singleton.h"
 #include "base/string_number_conversions.h"
 #include "base/utf_string_conversions.h"
@@ skipping 25 matching lines @@
 
   static void __stdcall SpeechEventCallback(WPARAM w_param, LPARAM l_param);
 
  private:
   ExtensionTtsPlatformImplWin();
   virtual ~ExtensionTtsPlatformImplWin() {}
 
   void OnSpeechEvent();
 
   base::win::ScopedComPtr<ISpVoice> speech_synthesizer_;
-  bool paused_;
 
   // These apply to the current utterance only.
   std::wstring utterance_;
   int utterance_id_;
   int prefix_len_;
   ULONG stream_number_;
   int char_position_;
 
   friend struct DefaultSingletonTraits<ExtensionTtsPlatformImplWin>;
 
@@ skipping 35 matching lines @@
         base::IntToString16(static_cast<int>(params.pitch * 10 - 10));
     prefix = L"<pitch absmiddle=\"" + pitch_value + L"\">";
     suffix = L"</pitch>";
   }
 
   if (params.volume >= 0.0) {
     // The TTS api allows a range of 0 to 100 for speech volume.
     speech_synthesizer_->SetVolume(static_cast<uint16>(params.volume * 100));
   }
 
-  if (paused_) {
-    speech_synthesizer_->Resume();
-    paused_ = false;
-  }
-
   // TODO(dmazzoni): convert SSML to SAPI xml. http://crbug.com/88072
 
   utterance_ = UTF8ToWide(src_utterance);
   utterance_id_ = utterance_id;
   char_position_ = 0;
   std::wstring merged_utterance = prefix + utterance_ + suffix;
   prefix_len_ = prefix.size();
 
-
   HRESULT result = speech_synthesizer_->Speak(
       merged_utterance.c_str(),
       SPF_ASYNC,
       &stream_number_);
   return (result == S_OK);
 }
 
 bool ExtensionTtsPlatformImplWin::StopSpeaking() {
-  if (speech_synthesizer_ && !paused_) {
+  if (speech_synthesizer_) {
     // Clear the stream number so that any further events relating to this
     // utterance are ignored.
     stream_number_ = 0;
 
-    speech_synthesizer_->Pause();
-    paused_ = true;
+    if (IsSpeaking()) {
+      // Stop speech by speaking the empty string with the purge flag.
+      speech_synthesizer_->Speak(L"", SPF_ASYNC | SPF_PURGEBEFORESPEAK, NULL);
+    }
   }
   return true;
 }
 
 bool ExtensionTtsPlatformImplWin::IsSpeaking() {
-  if (speech_synthesizer_ && !paused_) {
+  if (speech_synthesizer_) {
     SPVOICESTATUS status;
     HRESULT result = speech_synthesizer_->GetStatus(&status, NULL);
     if (result == S_OK) {
       if (status.dwRunningState == 0 ||  // 0 == waiting to speak
           status.dwRunningState == SPRS_IS_SPEAKING) {
         return true;
       }
     }
   }
   return false;
@@ skipping 38 matching lines @@
       char_position_ = static_cast<ULONG>(event.lParam) - prefix_len_;
       controller->OnTtsEvent(
           utterance_id_, TTS_EVENT_SENTENCE, char_position_,
           std::string());
       break;
     }
   }
 }
 
 ExtensionTtsPlatformImplWin::ExtensionTtsPlatformImplWin()
-  : speech_synthesizer_(NULL),
-    paused_(false) {
+  : speech_synthesizer_(NULL) {
   CoCreateInstance(
       CLSID_SpVoice,
       NULL,
       CLSCTX_SERVER,
       IID_ISpVoice,
       reinterpret_cast<void**>(&speech_synthesizer_));
   if (speech_synthesizer_) {
     ULONGLONG event_mask =
         SPFEI(SPEI_START_INPUT_STREAM) |
         SPFEI(SPEI_TTS_BOOKMARK) |
         SPFEI(SPEI_WORD_BOUNDARY) |
         SPFEI(SPEI_SENTENCE_BOUNDARY) |
         SPFEI(SPEI_END_INPUT_STREAM);
     speech_synthesizer_->SetInterest(event_mask, event_mask);
     speech_synthesizer_->SetNotifyCallbackFunction(
         ExtensionTtsPlatformImplWin::SpeechEventCallback, 0, 0);
   }
 }
 
 // static
 ExtensionTtsPlatformImplWin* ExtensionTtsPlatformImplWin::GetInstance() {
   return Singleton<ExtensionTtsPlatformImplWin>::get();
 }
 
 // static
 void ExtensionTtsPlatformImplWin::SpeechEventCallback(
     WPARAM w_param, LPARAM l_param) {
   GetInstance()->OnSpeechEvent();
 }