Eliminate the dependence of tts extension API form tts_controller.cc

chrome/browser/speech/tts_controller.h

Index: chrome/browser/speech/tts_controller.h
diff --git a/chrome/browser/speech/tts_controller.h b/chrome/browser/speech/tts_controller.h
index c8d1c10a4cf456421169892bce4b179ce896a20a..0962f67dfe88d324fcead32b749ca5a97c3276db 100644
--- a/chrome/browser/speech/tts_controller.h
+++ b/chrome/browser/speech/tts_controller.h
@@ -77,6 +77,29 @@ struct VoiceData {
   std::string native_voice_identifier;
 };
 
+// Interface that delegates TTS requests to user-installed extensions.
+class TtsEngineDelegate {
+ public:
+  virtual ~TtsEngineDelegate() {}
+
+  // Return a list of all available voices registered.
+  virtual void GetVoices(Profile* profile,
+                         std::vector<VoiceData>* out_voices) = 0;
+
+  // Speak the given utterance by sending an event to the given TTS engine.
+  virtual void Speak(Utterance* utterance, const VoiceData& voice) = 0;
+
+  // Stop speaking the given utterance by sending an event to the target
+  // associated with this utterance.
+  virtual void Stop(Utterance* utterance) = 0;
+
+  // Pause in the middle of speaking this utterance.
+  virtual void Pause(Utterance* utterance) = 0;
+
+  // Resume speaking this utterance.
+  virtual void Resume(Utterance* utterance) = 0;
+};
+
 // Class that wants to receive events on utterances.
 class UtteranceEventDelegate {
  public:
@@ -297,6 +320,10 @@ class TtsController {
   // Remove delegate that wants to be notified when the set of voices changes.
   void RemoveVoicesChangedDelegate(VoicesChangedDelegate* delegate);
 
+  // Set the delegate that processes TTS requests with user-installed
+  // extensions.
+  void SetTtsEngineDelegate(TtsEngineDelegate* delegate);
+
   // For unit testing.
   void SetPlatformImpl(TtsPlatformImpl* platform_impl);
   int QueueSize();
@@ -346,6 +373,9 @@ class TtsController {
   // dependency injection.
   TtsPlatformImpl* platform_impl_;
 
+  // The delegate that processes TTS requests with user-installed extensions.
+  TtsEngineDelegate* tts_engine_delegate_;
+
   DISALLOW_COPY_AND_ASSIGN(TtsController);
 };