Eliminate the dependence of tts extension API form tts_controller.cc

chrome/browser/speech/extension_api/tts_engine_extension_api.h

Index: chrome/browser/speech/extension_api/tts_engine_extension_api.h
diff --git a/chrome/browser/speech/extension_api/tts_engine_extension_api.h b/chrome/browser/speech/extension_api/tts_engine_extension_api.h
index 112c0e1b2f3bba0ec312edf760c68af194f20714..a2df6818e791042449e244444f667ae150b87512 100644
--- a/chrome/browser/speech/extension_api/tts_engine_extension_api.h
+++ b/chrome/browser/speech/extension_api/tts_engine_extension_api.h
@@ -28,32 +28,19 @@ extern const char kOnPause[];
 extern const char kOnResume[];
 }
 
-// Return a list of all available voices registered by extensions.
-void GetExtensionVoices(Profile* profile, std::vector<VoiceData>* out_voices);
-
-// Find the first extension with a tts_voices in its
-// manifest that matches the speech parameters of this utterance.
-// If found, store a pointer to the extension in |matching_extension| and
-// the index of the voice within the extension in |voice_index| and
-// return true.
-bool GetMatchingExtensionVoice(Utterance* utterance,
-                               const extensions::Extension** matching_extension,
-                               size_t* voice_index);
-
-// Speak the given utterance by sending an event to the given TTS engine
-// extension voice.
-void ExtensionTtsEngineSpeak(Utterance* utterance,
-                             const VoiceData& voice);
-
-// Stop speaking the given utterance by sending an event to the extension
-// associated with this utterance.
-void ExtensionTtsEngineStop(Utterance* utterance);
-
-// Pause in the middle of speaking this utterance.
-void ExtensionTtsEnginePause(Utterance* utterance);
-
-// Resume speaking this utterance.
-void ExtensionTtsEngineResume(Utterance* utterance);
+// TtsEngineDelegate implementation used by TtsController.
+class TtsExtensionEngine : public TtsEngineDelegate {
+ public:
+  static TtsExtensionEngine* GetInstance();
+
+  // Overridden from TtsEngineDelegate:
+  virtual void GetVoices(Profile* profile,
+                 std::vector<VoiceData>* out_voices) OVERRIDE;
+  virtual void Speak(Utterance* utterance, const VoiceData& voice) OVERRIDE;
+  virtual void Stop(Utterance* utterance) OVERRIDE;
+  virtual void Pause(Utterance* utterance) OVERRIDE;
+  virtual void Resume(Utterance* utterance) OVERRIDE;
+};
 
 // Hidden/internal extension function used to allow TTS engine extensions
 // to send events back to the client that's calling tts.speak().