Enable automatic resizing for RTX-enabled senders.

talk/media/webrtc/webrtcvideoengine2.cc

 /*
  * libjingle
  * Copyright 2014 Google Inc.
  *
  * Redistribution and use in source and binary forms, with or without
  * modification, are permitted provided that the following conditions are met:
  *
  *  1. Redistributions of source code must retain the above copyright notice,
  *     this list of conditions and the following disclaimer.
  *  2. Redistributions in binary form must reproduce the above copyright notice,
@@ skipping 469 matching lines @@
   stream.max_qp = max_qp;
   std::vector<webrtc::VideoStream> streams;
   streams.push_back(stream);
   return streams;
 }
 
 void* WebRtcVideoChannel2::WebRtcVideoSendStream::ConfigureVideoEncoderSettings(
     const VideoCodec& codec,
     const VideoOptions& options,
     bool is_screencast) {
-  // No automatic resizing when using simulcast.
-  bool automatic_resize = !is_screencast && ssrcs_.size() == 1;
+  // No automatic resizing when using simulcast or screencast.
+  bool automatic_resize =
+      !is_screencast && parameters_.config.rtp.ssrcs.size() == 1;
   bool frame_dropping = !is_screencast;
   bool denoising;
   if (is_screencast) {
     denoising = false;
   } else {
     options.video_noise_reduction.Get(&denoising);
   }
 
   if (CodecNamesEq(codec.name, kVp8CodecName)) {
     encoder_settings_.vp8 = webrtc::VideoEncoder::GetDefaultVp8Settings();
@@ skipping 2271 matching lines @@
       video_codecs[i].rtx_payload_type = rtx_mapping[video_codecs[i].codec.id];
     }
   }
 
   return video_codecs;
 }
 
 }  // namespace cricket
 
 #endif  // HAVE_WEBRTC_VIDEO