Support configuring the audio buffer duration in the Pepper MediaStream API.

content/renderer/pepper/pepper_media_stream_audio_track_host.h

Index: content/renderer/pepper/pepper_media_stream_audio_track_host.h
diff --git a/content/renderer/pepper/pepper_media_stream_audio_track_host.h b/content/renderer/pepper/pepper_media_stream_audio_track_host.h
index 348103c9928c55faa4c7beca1e0259b2347e07a4..5456cc7ec21902bb1704091ff0966a2029d582c0 100644
--- a/content/renderer/pepper/pepper_media_stream_audio_track_host.h
+++ b/content/renderer/pepper/pepper_media_stream_audio_track_host.h
@@ -45,11 +45,11 @@ class PepperMediaStreamAudioTrackHost : public PepperMediaStreamTrackHostBase {
     void EnqueueBuffer(int32_t index);
 
     // This function is called on the main thread.
-    void Configure(int32_t number_of_buffers);
+    void Configure(int32_t number_of_buffers, int32_t duration);
 
    private:
     // Initializes buffers on the main thread.
-    void SetFormatOnMainThread(int bytes_per_second);
+    void SetFormatOnMainThread(int bytes_per_second, int bytes_per_frame);
 
     void InitBuffers();
 
@@ -69,6 +69,9 @@ class PepperMediaStreamAudioTrackHost : public PepperMediaStreamTrackHostBase {
     // host_->buffer_manager() to read some buffer properties. It is safe
     // because the buffer_manager()'s properties will not be changed after
     // initialization.
+    // TODO(amistry): The last statement above is not true. The user can
+    // configure the audio track at any time, which may involve changing both
+    // the number and size of buffers.
     PepperMediaStreamAudioTrackHost* host_;
 
     // Timestamp of the next received audio buffer.
@@ -92,12 +95,28 @@ class PepperMediaStreamAudioTrackHost : public PepperMediaStreamTrackHostBase {
     // Access only on the audio thread.
     uint32_t buffer_data_size_;
 
-    // A lock to protect the index queue |buffers_|.
+    // Index of the currently active buffer.
+    // Access only on the audio thread.
+    int active_buffer_index_;
+
+    // Pointer to the currently active buffer. Used to detect when buffers
+    // change.
+    // Access only on the audio thread.
+    void* active_buffer_ptr_;
+
+    // Current offset, in bytes, within the currently active buffer.
+    // Access only on the audio thread.
+    uint32_t active_buffer_offset_;
+
+    // A lock to protect the index queue |buffers_| and |output_buffer_size_|.
     base::Lock lock_;
 
     // A queue for free buffer indices.
     std::deque<int32_t> buffers_;
 
+    // Intended size of each output buffer.
+    int32_t output_buffer_size_;
+
     scoped_refptr<base::MessageLoopProxy> main_message_loop_proxy_;
 
     base::ThreadChecker audio_thread_checker_;
@@ -110,6 +129,12 @@ class PepperMediaStreamAudioTrackHost : public PepperMediaStreamTrackHostBase {
     // Number of bytes per second.
     int bytes_per_second_;
 
+    // Number of bytes per frame = channels * bytes per sample.
+    int bytes_per_frame_;
+
+    // User-configured buffer duration, in milliseconds.
+    int32_t user_buffer_duration_;
+
     DISALLOW_COPY_AND_ASSIGN(AudioSink);
   };