New flag is_screencast in VideoOptions.

webrtc/video/video_send_stream.cc

Index: webrtc/video/video_send_stream.cc
diff --git a/webrtc/video/video_send_stream.cc b/webrtc/video/video_send_stream.cc
index 58ed646363ebbee899656dbb95731eeeeaa36d2a..8e0e04fb12a6457fdcce6e665b9ad51739c3f715 100644
--- a/webrtc/video/video_send_stream.cc
+++ b/webrtc/video/video_send_stream.cc
@@ -474,9 +474,12 @@ bool VideoSendStream::ReconfigureVideoEncoder(
   RTC_DCHECK_GT(streams[0].max_framerate, 0);
   video_codec.maxFramerate = streams[0].max_framerate;
 
-  if (!SetSendCodec(video_codec))
+  if (!SetSendCodec(video_codec)) {
+    LOG(LS_WARNING) << "(Re)configureVideoEncoder: SetSendCodec failed "
+                       "for config: "
+                    << config.ToString();
     return false;
-
+  }
   // Clear stats for disabled layers.
   for (size_t i = video_codec.numberOfSimulcastStreams;
        i < config_.rtp.ssrcs.size(); ++i) {