Use simulcast for screenshare only in conference mode

webrtc/media/engine/webrtcvideoengine2.cc

 /*
  *  Copyright (c) 2014 The WebRTC project authors. All Rights Reserved.
  *
  *  Use of this source code is governed by a BSD-style license
  *  that can be found in the LICENSE file in the root of the source
  *  tree. An additional intellectual property rights grant can be found
  *  in the file PATENTS.  All contributing project authors may
  *  be found in the AUTHORS file in the root of the source tree.
  */
 
@@ skipping 1854 matching lines @@
     encoder_config.content_type =
         webrtc::VideoEncoderConfig::ContentType::kRealtimeVideo;
   }
 
   // By default, the stream count for the codec configuration should match the
   // number of negotiated ssrcs. But if the codec is blacklisted for simulcast
   // or a screencast (and not in simulcast screenshare experiment), only
   // configure a single stream.
   encoder_config.number_of_streams = parameters_.config.rtp.ssrcs.size();
   if (IsCodecBlacklistedForSimulcast(codec.name) ||
-      (is_screencast && !UseSimulcastScreenshare())) {
+      (is_screencast &&
+       (!UseSimulcastScreenshare() || !parameters_.conference_mode))) {
     encoder_config.number_of_streams = 1;
   }
 
   int stream_max_bitrate = parameters_.max_bitrate_bps;
   if (rtp_parameters_.encodings[0].max_bitrate_bps) {
     stream_max_bitrate =
         MinPositive(*(rtp_parameters_.encodings[0].max_bitrate_bps),
                     parameters_.max_bitrate_bps);
   }
 
   int codec_max_bitrate_kbps;
   if (codec.GetParam(kCodecParamMaxBitrate, &codec_max_bitrate_kbps)) {
     stream_max_bitrate = codec_max_bitrate_kbps * 1000;
   }
   encoder_config.max_bitrate_bps = stream_max_bitrate;
 
   int max_qp = kDefaultQpMax;
   codec.GetParam(kCodecParamMaxQuantization, &max_qp);
   encoder_config.video_stream_factory =
       new rtc::RefCountedObject<EncoderStreamFactory>(
           codec.name, max_qp, kDefaultVideoMaxFramerate, is_screencast,
           parameters_.conference_mode);
   return encoder_config;
 }
 
 void WebRtcVideoChannel2::WebRtcVideoSendStream::ReconfigureEncoder() {
   RTC_DCHECK_RUN_ON(&thread_checker_);
   if (!stream_) {
-    // The webrtc::VideoSendStream |stream_|has not yet been created but other
+    // The webrtc::VideoSendStream |stream_| has not yet been created but other
     // parameters has changed.
     return;
   }
 
   RTC_DCHECK_GT(parameters_.encoder_config.number_of_streams, 0);
 
   RTC_CHECK(parameters_.codec_settings);
   VideoCodecSettings codec_settings = *parameters_.codec_settings;
 
   webrtc::VideoEncoderConfig encoder_config =
@@ skipping 627 matching lines @@
         rtx_mapping[video_codecs[i].codec.id] !=
             ulpfec_config.red_payload_type) {
       video_codecs[i].rtx_payload_type = rtx_mapping[video_codecs[i].codec.id];
     }
   }
 
   return video_codecs;
 }
 
 }  // namespace cricket