Added a kEchoCancellation constraint to turn off the audio processing.

content/renderer/media/webrtc_audio_capturer.cc

Index: content/renderer/media/webrtc_audio_capturer.cc
diff --git a/content/renderer/media/webrtc_audio_capturer.cc b/content/renderer/media/webrtc_audio_capturer.cc
index 482d25f1114b2479baabcda0d4fb930c4e5ba944..1548fd123b9c4a11984845a63a1943cc33a62f26 100644
--- a/content/renderer/media/webrtc_audio_capturer.cc
+++ b/content/renderer/media/webrtc_audio_capturer.cc
@@ -163,6 +163,13 @@ bool WebRtcAudioCapturer::Initialize() {
     return true;
   }
 
+  MediaAudioConstraints audio_constraints(constraints_,
+                                          device_info_.device.input.effects);
+  if (!audio_constraints.IsValid()) {
+    DLOG(ERROR) << "Constraints contain invalid mandatory keys";

[perkj_chrome, 2014/04/15 13:01:06]

This is already logged in !audio_constraints.IsValid.

[no longer working on chromium, 2014/04/23 14:59:06]

OK, I removed it.

+    return false;
+  }
+
   media::ChannelLayout channel_layout = static_cast<media::ChannelLayout>(
       device_info_.device.input.channel_layout);
   DVLOG(1) << "Audio input hardware channel layout: " << channel_layout;
@@ -220,8 +227,7 @@ WebRtcAudioCapturer::WebRtcAudioCapturer(
     : constraints_(constraints),
       audio_processor_(
           new talk_base::RefCountedObject<MediaStreamAudioProcessor>(
-              constraints, device_info.device.input.effects,
-              device_info.device.type, audio_device)),
+              constraints, device_info.device.input.effects, audio_device)),
       running_(false),
       render_view_id_(render_view_id),
       device_info_(device_info),
@@ -320,8 +326,9 @@ void WebRtcAudioCapturer::SetCapturerSource(
     // Notify the |audio_processor_| of the new format.
     audio_processor_->OnCaptureFormatChanged(params);
 
-    need_audio_processing_ = NeedsAudioProcessing(
-        constraints_, device_info_.device.input.effects);
+    MediaAudioConstraints audio_constraints(constraints_,
+                                            device_info_.device.input.effects);
+    need_audio_processing_ = audio_constraints.NeedsAudioProcessing();
     // Notify all tracks about the new format.
     tracks_.TagAll();
   }