Added a kEchoCancellation constraint to turn off the audio processing.

content/renderer/media/media_stream_audio_processor.h

Index: content/renderer/media/media_stream_audio_processor.h
diff --git a/content/renderer/media/media_stream_audio_processor.h b/content/renderer/media/media_stream_audio_processor.h
index 2233007bc1dcdc7e855003d4c2f0dea027e8f361..56208782b0c637142ed936a31dab19a108e31b3f 100644
--- a/content/renderer/media/media_stream_audio_processor.h
+++ b/content/renderer/media/media_stream_audio_processor.h
@@ -11,7 +11,6 @@
 #include "base/threading/thread_checker.h"
 #include "base/time/time.h"
 #include "content/common/content_export.h"
-#include "content/public/common/media_stream_request.h"
 #include "content/renderer/media/webrtc_audio_device_impl.h"
 #include "media/base/audio_converter.h"
 #include "third_party/libjingle/source/talk/app/webrtc/mediastreaminterface.h"
@@ -56,7 +55,6 @@ class CONTENT_EXPORT MediaStreamAudioProcessor :
   // |playout_data_source| won't be used.
   MediaStreamAudioProcessor(const blink::WebMediaConstraints& constraints,
                             int effects,
-                            MediaStreamType type,
                             WebRtcPlayoutDataSource* playout_data_source);
 
   // Called when format of the capture data has changed.
@@ -125,8 +123,7 @@ class CONTENT_EXPORT MediaStreamAudioProcessor :
 
   // Helper to initialize the WebRtc AudioProcessing.
   void InitializeAudioProcessingModule(
-      const blink::WebMediaConstraints& constraints, int effects,
-      MediaStreamType type);
+      const blink::WebMediaConstraints& constraints, int effects);
 
   // Helper to initialize the capture converter.
   void InitializeCaptureConverter(const media::AudioParameters& source_params);