Mac Video Capture: Connect error logging to WebRTC Log

media/video/capture/video_capture_device.h

Index: media/video/capture/video_capture_device.h
diff --git a/media/video/capture/video_capture_device.h b/media/video/capture/video_capture_device.h
index 7651d04b53e4ebf2b18b793e19c60970f4e859c0..afb4c3567ac3362a9a9cae08c14fada1b507067a 100644
--- a/media/video/capture/video_capture_device.h
+++ b/media/video/capture/video_capture_device.h
@@ -187,6 +187,9 @@ class MEDIA_EXPORT VideoCaptureDevice {
     // An error has occurred that cannot be handled and VideoCaptureDevice must
     // be StopAndDeAllocate()-ed. |reason| is a text description of the error.
     virtual void OnError(const std::string& reason) = 0;
+
+    // VideoCaptureDevice requests the |message| to be logged.
+    virtual void OnLog(const std::string& message) {}
   };
 
   // Creates a VideoCaptureDevice object.