Create a private API for controlling WebRTC's AEC3

content/renderer/media/media_stream_audio_processor.cc

Index: content/renderer/media/media_stream_audio_processor.cc
diff --git a/content/renderer/media/media_stream_audio_processor.cc b/content/renderer/media/media_stream_audio_processor.cc
index 46d742807bd5c20e4b6fba0bb13223cea158244d..2a518cb24ef2bef237bb990202f845b4ee626228 100644
--- a/content/renderer/media/media_stream_audio_processor.cc
+++ b/content/renderer/media/media_stream_audio_processor.cc
@@ -486,6 +486,25 @@ void MediaStreamAudioProcessor::OnDisableAecDump() {
     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 17:08:40]

Nit: can be written
if (override_aec3_ == enable)

[hlundin-chromium, 2017/04/11 09:19:37]

Done.

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

[Henrik Grunell, 2017/04/10 17:08:40]

Nit: override_aec3_ = enable;

[hlundin-chromium, 2017/04/11 09:19:37]

Done.

+  if (!has_echo_cancellation_)
+    return;
+
+  auto apm_config = audio_processing_->GetConfig();
+  if (apm_config.echo_canceller3.enabled == enable)
+    return;
+
+  apm_config.echo_canceller3.enabled = enable;
+  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;
@@ -596,6 +615,7 @@ void MediaStreamAudioProcessor::InitializeAudioProcessingModule(
 
   const bool echo_cancellation =
       audio_constraints.GetEchoCancellationProperty();
+  has_echo_cancellation_ = echo_cancellation;
   const bool goog_agc = audio_constraints.GetGoogAutoGainControl();
 
 #if defined(OS_ANDROID)
@@ -680,7 +700,9 @@ void MediaStreamAudioProcessor::InitializeAudioProcessingModule(
     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;
   }