Possible solution to synchronization problems in webrtc audio capturer.

content/renderer/media/webrtc_audio_capturer.h

Index: content/renderer/media/webrtc_audio_capturer.h
diff --git a/content/renderer/media/webrtc_audio_capturer.h b/content/renderer/media/webrtc_audio_capturer.h
index afb072f5f7ab8204e1863eff744ac7d889ce963b..787a0470993ddb49aa60d3ca2d19a043f474ec62 100644
--- a/content/renderer/media/webrtc_audio_capturer.h
+++ b/content/renderer/media/webrtc_audio_capturer.h
@@ -136,7 +136,7 @@ class CONTENT_EXPORT WebRtcAudioCapturer
   // Audio parameters utilized by the audio capturer. Can be utilized by
   // a local renderer to set up a renderer using identical parameters as the
   // capturer.

[phoglund_chromium, 2013/02/08 16:10:38]

Removing const looks silly, but I actually have to now since this one grabs a
lock.

[tommi (sloooow) - chröme, 2013/02/08 16:32:04]

You could make the lock mutable which is common in cases like this. 

However, since audio_parameters() returns a pointer to a variable owned by a
reference counted object that we're using a lock to access, then the returned
reference here cannot be trusted.  So, I'm not sure this accessor is a good
idea.

[phoglund_chromium, 2013/02/08 17:06:00]

Yeah, I wrote a TODO on the accessor.

-  const media::AudioParameters& audio_parameter() const { return params_; }
+  const media::AudioParameters& audio_parameter();

[tommi (sloooow) - chröme, 2013/02/08 16:32:04]

nit: audio_parameters() (plural) or just params() as you do in the cc file.

[phoglund_chromium, 2013/02/08 17:06:00]

Done.

 
   // AudioCapturerSource::CaptureCallback implementation.
   // Called on the AudioInputDevice audio thread.
@@ -165,11 +165,16 @@ class CONTENT_EXPORT WebRtcAudioCapturer
 
   WebRtcAudioCapturer();
 
+  // Reconfigures the capturer with a new buffer size and capture parameters.
+  // Must be called without holding the lock. Returns true on success.
+  bool Reconfigure(int sample_rate, media::AudioParameters::Format format,
+                   media::ChannelLayout channel_layout);
+
   // Used to DCHECK that we are called on the correct thread.
   base::ThreadChecker thread_checker_;
 
   // Protects |source_|, |sinks_|, |running_|, |on_device_stopped_cb_|,
-  // |loopback_fifo_| and |buffering_|.
+  // |loopback_fifo_|, |params_| and |buffering_|.
   base::Lock lock_;
 
   // A list of sinks that the audio data is fed to.
@@ -178,12 +183,10 @@ class CONTENT_EXPORT WebRtcAudioCapturer
   // The audio data source from the browser process.
   scoped_refptr<media::AudioCapturerSource> source_;
 
-  // Cached values of utilized audio parameters. Platform dependent.
-  media::AudioParameters params_;
-
   // Buffers used for temporary storage during capture callbacks.
   // Allocated during initialization.
-  scoped_array<int16> buffer_;
+  class ConfiguredBuffer;
+  scoped_refptr<ConfiguredBuffer> buffer_;
   std::string device_id_;
   bool running_;