Create a private API for controlling WebRTC's AEC3

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 468 matching lines @@
   else
     file.Close();
 }
 
 void MediaStreamAudioProcessor::OnDisableAecDump() {
   DCHECK(main_thread_runner_->BelongsToCurrentThread());
   if (audio_processing_)
     StopEchoCancellationDump(audio_processing_.get());
 }
 
+void MediaStreamAudioProcessor::OnAec3Enable(bool enable) {
+  DCHECK(main_thread_runner_->BelongsToCurrentThread());
+  if (override_aec3_ != base::Optional<bool>(enable)) {

[Henrik Grunell, 2017/04/10 08:13:28]

Early returns instead in this function, e.g.

if (override_aec3_ == base::Optional<bool>(enable))
  return;

...

[hlundin-chromium, 2017/04/10 10:10:16]

Done.

+    override_aec3_ = base::Optional<bool>(enable);
+    if (has_echo_cancellation_) {
+      DCHECK(audio_processing_);

[Henrik Grunell, 2017/04/10 08:13:28]

Remove (redundant). It will crash on the next line if not set.

[hlundin-chromium, 2017/04/10 10:10:16]

Done.

+      auto apm_config = audio_processing_->GetConfig();
+      if (apm_config.echo_canceller3.enabled != enable) {
+        apm_config.echo_canceller3.enabled = enable;

[Henrik Grunell, 2017/04/10 08:13:28]

I'm not sure how this is supposed to work. If not overridden, should it not go
back to  the features::kWebRtcUseEchoCanceller3 value?

[hlundin-chromium, 2017/04/10 10:10:16]

If not overridden, it will already be at the value determined by
features::kWebRtcUseEchoCanceller3.

[Henrik Grunell, 2017/04/10 12:33:47]

I realized that it can never be un-overridden. Setting it via the API means that
it overrides. Fine.

+        audio_processing_->ApplyConfig(apm_config);
+        DCHECK(echo_information_);
+        echo_information_.reset(new EchoInformation());
+      }
+    }
+  }
+}
+
 void MediaStreamAudioProcessor::OnIpcClosing() {
   DCHECK(main_thread_runner_->BelongsToCurrentThread());
   aec_dump_message_filter_ = NULL;
 }
 
 // static
 bool MediaStreamAudioProcessor::WouldModifyAudio(
     const blink::WebMediaConstraints& constraints,
     int effects_flags) {
   // Note: This method should by kept in-sync with any changes to the logic in
@@ skipping 90 matching lines @@
 
   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,
   // require webrtc::AudioProcessing.
   audio_mirroring_ = audio_constraints.GetGoogAudioMirroring();
 
   const bool echo_cancellation =
       audio_constraints.GetEchoCancellationProperty();
+  has_echo_cancellation_ = echo_cancellation;
   const bool goog_agc = audio_constraints.GetGoogAutoGainControl();
 
 #if defined(OS_ANDROID)
   const bool goog_experimental_aec = false;
   const bool goog_typing_detection = false;
 #else
   const bool goog_experimental_aec =
       audio_constraints.GetGoogExperimentalEchoCancellation();
   const bool goog_typing_detection =
       audio_constraints.GetGoogTypingNoiseDetection();
@@ skipping 64 matching lines @@
   }
 
   if (echo_cancellation) {
     EnableEchoCancellation(audio_processing_.get());
 
     // 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(features::kWebRtcUseEchoCanceller3);
+        override_aec3_
+            ? *override_aec3_
+            : base::FeatureList::IsEnabled(features::kWebRtcUseEchoCanceller3);
   } 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;
@@ skipping 176 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