Added a kEchoCancellation constraint to turn off the audio processing.

content/renderer/media/media_stream_dependency_factory.cc

 // Copyright (c) 2012 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_dependency_factory.h"
 
 #include <vector>
 
 #include "base/command_line.h"
 #include "base/strings/utf_string_conversions.h"
@@ skipping 175 matching lines @@
 
 bool MediaStreamDependencyFactory::InitializeMediaStreamAudioSource(
     int render_view_id,
     const blink::WebMediaConstraints& audio_constraints,
     MediaStreamAudioSource* source_data) {
   DVLOG(1) << "InitializeMediaStreamAudioSources()";
 
   // Do additional source initialization if the audio source is a valid
   // microphone or tab audio.
   RTCMediaConstraints native_audio_constraints(audio_constraints);
-  ApplyFixedAudioConstraints(&native_audio_constraints);
+  MediaAudioConstraints::ApplyFixedAudioConstraints(&native_audio_constraints);
 
   StreamDeviceInfo device_info = source_data->device_info();
   RTCMediaConstraints constraints = native_audio_constraints;
   // May modify both |constraints| and |effects|.
   HarmonizeConstraintsAndEffects(&constraints,
                                  &device_info.device.input.effects);
 
   scoped_refptr<WebRtcAudioCapturer> capturer(
       CreateAudioCapturer(render_view_id, device_info, audio_constraints,
                           source_data));
@@ skipping 453 matching lines @@
 }
 
 void MediaStreamDependencyFactory::EnsureWebRtcAudioDeviceImpl() {
   if (audio_device_)
     return;
 
   audio_device_ = new WebRtcAudioDeviceImpl();
 }
 
 }  // namespace content