Added a kEchoCancellation constraint to turn off the audio processing.

content/renderer/media/webrtc_audio_capturer_unittest.cc

Index: content/renderer/media/webrtc_audio_capturer_unittest.cc
diff --git a/content/renderer/media/webrtc_audio_capturer_unittest.cc b/content/renderer/media/webrtc_audio_capturer_unittest.cc
index 11a017c021d81d634f8ce0e760621cc11dfb459d..4a7ed23626a43823c3d0e8d49a1a861710e89a2e 100644
--- a/content/renderer/media/webrtc_audio_capturer_unittest.cc
+++ b/content/renderer/media/webrtc_audio_capturer_unittest.cc
@@ -160,8 +160,8 @@ class WebRtcAudioCapturerTest : public testing::Test {
 // those values should be correctly stored and passed to the track.
 TEST_F(WebRtcAudioCapturerTest, VerifyAudioParams) {
   // Use constraints with default settings.
-  blink::WebMediaConstraints constraints;
-  VerifyAudioParams(constraints, true);
+  MockMediaConstraintFactory constraint_factory;
+  VerifyAudioParams(constraint_factory.CreateWebMediaConstraints(), true);
 }
 
 TEST_F(WebRtcAudioCapturerTest, VerifyAudioParamsWithAudioProcessing) {