Fix selection of "no audio processing" mode.

content/renderer/media/media_stream_audio_processor_options.h

Index: content/renderer/media/media_stream_audio_processor_options.h
diff --git a/content/renderer/media/media_stream_audio_processor_options.h b/content/renderer/media/media_stream_audio_processor_options.h
index bb2a54e7c605d54e83cf5bf81d3e1168b8bb8050..2d5af1d4f41261f97fba8ace5a9072c6677499cc 100644
--- a/content/renderer/media/media_stream_audio_processor_options.h
+++ b/content/renderer/media/media_stream_audio_processor_options.h
@@ -83,6 +83,11 @@ class CONTENT_EXPORT MediaAudioConstraints {
   // Otherwise return false.
   bool IsValid() const;
 
+  // Exposed for testing.
+  bool default_audio_processing_constraint_value() const {
+    return default_audio_processing_constraint_value_;
+  }
+
  private:
   // Gets the default value of constraint named by |key| in |constraints|.
   bool GetDefaultValueForConstraint(const std::string& key) const;