MediaStream audio: Refactor 3 separate "glue" implementations into one.

content/renderer/media/media_stream_audio_processor.cc

 // Copyright 2013 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #include "content/renderer/media/media_stream_audio_processor.h"
 
 #include <stddef.h>
 #include <stdint.h>
 #include <utility>
 
@@ skipping 284 matching lines @@
   for (int time = kMaxLookbackTimeMs; time >= kMinLookbackTimeMs;
        time -= kLookbackTimeStepMs) {
     look_back_times.push_back(time);
   }
   audio_repetition_detector_.reset(
       new AudioRepetitionDetector(kMinLengthMs, kMaxFrames, look_back_times,
                                   base::Bind(&ReportRepetition)));
 }
 
 MediaStreamAudioProcessor::~MediaStreamAudioProcessor() {
+  // TODO(miu): This class is ref-counted, shared among threads, and then
+  // requires itself to be destroyed on the main thread only?!?!? Fix this, and
+  // then remove the hack in WebRtcAudioSink::Adapter.
   DCHECK(main_thread_checker_.CalledOnValidThread());
   Stop();
 }
 
 void MediaStreamAudioProcessor::OnCaptureFormatChanged(
     const media::AudioParameters& input_format) {
   DCHECK(main_thread_checker_.CalledOnValidThread());
   // There is no need to hold a lock here since the caller guarantees that
   // there is no more PushCaptureData() and ProcessAndConsumeData() callbacks
   // on the capture thread.
@@ skipping 424 matching lines @@
   if (echo_information_) {
     echo_information_.get()->UpdateAecDelayStats(ap->echo_cancellation());
   }
 
   // Return 0 if the volume hasn't been changed, and otherwise the new volume.
   return (agc->stream_analog_level() == volume) ?
       0 : agc->stream_analog_level();
 }
 
 }  // namespace content