Added a kEchoCancellation constraint to turn off the audio processing.

content/renderer/media/media_stream_video_source_unittest.cc

Index: content/renderer/media/media_stream_video_source_unittest.cc
diff --git a/content/renderer/media/media_stream_video_source_unittest.cc b/content/renderer/media/media_stream_video_source_unittest.cc
index c6e4bf8418b19e5fe7f9e1314fd1d2e6c7529f06..fd691a7acccacb6b6488a2efb6f6bc8dacfd891b 100644
--- a/content/renderer/media/media_stream_video_source_unittest.cc
+++ b/content/renderer/media/media_stream_video_source_unittest.cc
@@ -96,7 +96,7 @@ class MediaStreamVideoSourceTest
                            int expected_height) {
     // Expect the source to start capture with the supported resolution.
     blink::WebMediaStreamTrack track =
-        CreateTrackAndStartSource(constraints, capture_width, capture_height ,
+        CreateTrackAndStartSource(constraints, capture_width, capture_height,
                                   30);
 
     MockMediaStreamVideoSink sink;