6 files changed, 34 insertions, 8 deletions
diff --git a/media/audio/audio_output.h b/media/audio/audio_output.h
index 0cfca08..289b2af 100644
--- a/media/audio/audio_output.h
+++ b/media/audio/audio_output.h
@@ -42,8 +42,11 @@
 class AudioOutputStream {
  public:
   enum State {
-    STATE_STARTED = 0,  // The output stream is started.
+    STATE_CREATED = 0,  // The output stream is created.
+    STATE_STARTED,      // The output stream is started.
     STATE_PAUSED,       // The output stream is paused.
+    STATE_STOPPED,      // The output stream is stopped.
+    STATE_CLOSED,       // The output stream is closed.
     STATE_ERROR,        // The output stream is in error state.
   };
 
@@ -82,6 +85,10 @@ class AudioOutputStream {
   virtual bool Open(size_t packet_size) = 0;
 
   // Starts playing audio and generating AudioSourceCallback::OnMoreData().
+  // Since implementor of AudioOutputStream may have internal buffers, right
+  // after calling this method initial buffers are fetched. User of this
+  // object should prepare |AudioOutputStream::GetNumBuffers()| before calling
+  // AudioOutputStream::Start().
   virtual void Start(AudioSourceCallback* callback) = 0;
 
   // Stops playing audio. Effect might no be instantaneous as the hardware
@@ -100,6 +107,11 @@ class AudioOutputStream {
   // After calling this method, the object should not be used anymore.
   virtual void Close() = 0;
 
+  // Gets the number of internal buffers used in this output stream. This
+  // method is useful for providing information about how user of this object
+  // should prepare initial buffers before calling AudioOutputStream::Start().
+  virtual size_t GetNumBuffers() = 0;
+
  protected:
   virtual ~AudioOutputStream() {}
 };
diff --git a/media/audio/mac/audio_output_mac.cc b/media/audio/mac/audio_output_mac.cc
index 3866a56..da6772f 100644
--- a/media/audio/mac/audio_output_mac.cc
+++ b/media/audio/mac/audio_output_mac.cc
@@ -9,7 +9,7 @@
 
 PCMQueueOutAudioOutputStream::PCMQueueOutAudioOutputStream(
     AudioManagerMac* manager, int channels, int sampling_rate,
-    char bits_per_sample) 
+    char bits_per_sample)
         : format_(),
           audio_queue_(NULL),
           buffer_(),
@@ -91,7 +91,7 @@ void PCMQueueOutAudioOutputStream::Close() {
 }
 
 void PCMQueueOutAudioOutputStream::Stop() {
-  // TODO(cpu): Implement.  
+  // TODO(cpu): Implement.
 }
 
 void PCMQueueOutAudioOutputStream::SetVolume(double left_level,
@@ -104,6 +104,10 @@ void PCMQueueOutAudioOutputStream::GetVolume(double* left_level,
   // TODO(cpu): Implement.
 }
 
+size_t PCMQueueOutAudioOutputStream::GetNumBuffers() {
+  return kNumBuffers;
+}
+
 void PCMQueueOutAudioOutputStream::RenderCallback(void* p_this,
                                                   AudioQueueRef queue,
                                                   AudioQueueBufferRef buffer) {
diff --git a/media/audio/mac/audio_output_mac.h b/media/audio/mac/audio_output_mac.h
index eb3c091..d1129b3 100644
--- a/media/audio/mac/audio_output_mac.h
+++ b/media/audio/mac/audio_output_mac.h
@@ -25,9 +25,9 @@ class PCMQueueOutAudioOutputStream : public AudioOutputStream {
                                int channels, int sampling_rate,
                                char bits_per_sample);
   // The dtor is typically called by the AudioManager only and it is usually
-  // triggered by calling AudioOutputStream::Close(). 
+  // triggered by calling AudioOutputStream::Close().
   virtual ~PCMQueueOutAudioOutputStream();
-  
+
   // Implementation of AudioOutputStream.
   virtual bool Open(size_t packet_size);
   virtual void Close();
@@ -35,11 +35,12 @@ class PCMQueueOutAudioOutputStream : public AudioOutputStream {
   virtual void Stop();
   virtual void SetVolume(double left_level, double right_level);
   virtual void GetVolume(double* left_level, double* right_level);
-  
+  virtual size_t GetNumBuffers();
+
  private:
   // The audio is double buffered.
   static const size_t kNumBuffers = 2;
-  
+
   // The OS calls back here when an audio buffer has been processed.
   static void RenderCallback(void* p_this, AudioQueueRef queue,
                              AudioQueueBufferRef buffer);
@@ -56,7 +57,7 @@ class PCMQueueOutAudioOutputStream : public AudioOutputStream {
   AudioSourceCallback* source_;
   // Our creator, the audio manager needs to be notified when we close.
   AudioManagerMac* manager_;
-  
+
   DISALLOW_COPY_AND_ASSIGN(PCMQueueOutAudioOutputStream);
 };
 
diff --git a/media/audio/win/audio_output_win.cc b/media/audio/win/audio_output_win.cc
index 880555b..5990e27 100644
--- a/media/audio/win/audio_output_win.cc
+++ b/media/audio/win/audio_output_win.cc
@@ -61,6 +61,10 @@ class AudioOutputStreamMockWin : public AudioOutputStream {
     *right_level = right_volume_;
   }
 
+  virtual size_t GetNumBuffers() {
+    return 1;
+  }
+
   virtual void Close() {
     callback_->OnClose(this);
     callback_ = NULL;
diff --git a/media/audio/win/waveout_output_win.cc b/media/audio/win/waveout_output_win.cc
index 95f70ab..59efa4e 100644
--- a/media/audio/win/waveout_output_win.cc
+++ b/media/audio/win/waveout_output_win.cc
@@ -193,6 +193,10 @@ void PCMWaveOutAudioOutputStream::GetVolume(double* left_level,
     return;
 }
 
+size_t PCMWaveOutAudioOutputStream::GetNumBuffers() {
+  return kNumBuffers;
+}
+
 void PCMWaveOutAudioOutputStream::HandleError(MMRESULT error) {
   DLOG(WARNING) << "PCMWaveOutAudio error " << error;
   callback_->OnError(this, error);
diff --git a/media/audio/win/waveout_output_win.h b/media/audio/win/waveout_output_win.h
index 1c8ffa6..8b90e69 100644
--- a/media/audio/win/waveout_output_win.h
+++ b/media/audio/win/waveout_output_win.h
@@ -40,6 +40,7 @@ class PCMWaveOutAudioOutputStream : public AudioOutputStream {
   virtual void Stop();
   virtual void SetVolume(double left_level, double right_level);
   virtual void GetVolume(double* left_level, double* right_level);
+  virtual size_t GetNumBuffers();
 
   // Sends a buffer to the audio driver for playback.
   void QueueNextPacket(WAVEHDR* buffer);