Adding functionality for activating for the WebRTC EchoCanceller3 functionality in Chrome.

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 562 matching lines @@
   DCHECK(render_thread_checker_.CalledOnValidThread());
   render_fifo_->ReattachThreadChecker();
 }
 
 void MediaStreamAudioProcessor::GetStats(AudioProcessorStats* stats) {
   stats->typing_noise_detected =
       (base::subtle::Acquire_Load(&typing_detected_) != false);
   GetAudioProcessingStats(audio_processing_.get(), stats);
 }
 
+// Features for http://crbug.com/688388. This value is sent to WebRTC's echo

[hlundin-chromium, 2017/02/09 10:20:45]

Move this information to content_features.{h|cc}.

[peah, 2017/02/15 13:24:24]

Done.

+// canceller to toggle which echo canceller should be used.
+const base::Feature kUseEchoCanceller3{"UseEchoCanceller3",

[hlundin-chromium, 2017/02/09 10:20:45]

You are defining this feature twice: here and in content_features.{h,cc}. I
think the pattern is to use one of them. I can only guess that you must define
it in content_features in order to connect it to chrome://flags, which means you
should delete this one. Instead, you will have to include
#include "content/public/common/content_features.h"
in this file.

[peah, 2017/02/15 13:24:24]

Thanks! Great suggestion!

Done.

+                                       base::FEATURE_DISABLED_BY_DEFAULT};
+
 void MediaStreamAudioProcessor::InitializeAudioProcessingModule(
     const blink::WebMediaConstraints& constraints,
     const MediaStreamDevice::AudioDeviceParameters& input_params) {
   DCHECK(main_thread_runner_->BelongsToCurrentThread());
   DCHECK(!audio_processing_);
 
   MediaAudioConstraints audio_constraints(constraints, input_params.effects);
 
   // Note: The audio mirroring constraint (i.e., swap left and right channels)
   // is handled within this MediaStreamAudioProcessor and does not, by itself,
@@ skipping 76 matching lines @@
 
   if (echo_cancellation) {
     EnableEchoCancellation(audio_processing_.get());
 
     if (playout_data_source_)
       playout_data_source_->AddPlayoutSink(this);
 
     // Prepare for logging echo information. If there are data remaining in
     // |echo_information_| we simply discard it.
     echo_information_.reset(new EchoInformation());
+
+    apm_config.echo_canceller3.enabled =
+        base::FeatureList::IsEnabled(kUseEchoCanceller3);
+  } else {
+    apm_config.echo_canceller3.enabled = false;
   }
 
   if (goog_ns) {
     // The beamforming postfilter is effective at suppressing stationary noise,
     // so reduce the single-channel NS aggressiveness when enabled.
     const NoiseSuppression::Level ns_level =
         config.Get<webrtc::Beamforming>().enabled ? NoiseSuppression::kLow
                                                   : NoiseSuppression::kHigh;
 
     EnableNoiseSuppression(audio_processing_.get(), ns_level);
@@ skipping 174 matching lines @@
       0 : agc->stream_analog_level();
 }
 
 void MediaStreamAudioProcessor::UpdateAecStats() {
   DCHECK(main_thread_runner_->BelongsToCurrentThread());
   if (echo_information_)
     echo_information_->UpdateAecStats(audio_processing_->echo_cancellation());
 }
 
 }  // namespace content