Rename RtpRtcp::Configuration::media_send_ssrc to local_media_ssrc

The name media_send_ssrc makes less sense when used mostly for the
RtcpReceiver functionality.

The old member is still there and used as a fallback. That will be
cleaned away after downstream code is fixed.

Bug: webrtc:10774
Change-Id: I4ec18db76910f31dfe76bc9b137ffe89220d3fa8
Reviewed-on: https://webrtc-review.googlesource.com/c/src/+/149836
Reviewed-by: Sebastian Jansson <srte@webrtc.org>
Reviewed-by: Fredrik Solenberg <solenberg@webrtc.org>
Commit-Queue: Erik Språng <sprang@webrtc.org>
Cr-Commit-Position: refs/heads/master@{#28923}
diff --git a/modules/rtp_rtcp/source/rtcp_receiver.cc b/modules/rtp_rtcp/source/rtcp_receiver.cc
index 69cb44f..20cfb8f 100644
--- a/modules/rtp_rtcp/source/rtcp_receiver.cc
+++ b/modules/rtp_rtcp/source/rtcp_receiver.cc
@@ -137,7 +137,8 @@
                               ? config.rtcp_report_interval_ms
                               : (config.audio ? kDefaultAudioReportInterval
                                               : kDefaultVideoReportInterval)),
-      main_ssrc_(config.media_send_ssrc.value_or(0)),
+      // TODO(bugs.webrtc.org/10774): Remove fallback.
+      main_ssrc_(config.get_local_media_ssrc().value_or(0)),
       remote_ssrc_(0),
       remote_sender_rtp_time_(0),
       xr_rrtr_status_(false),
@@ -152,8 +153,8 @@
       num_skipped_packets_(0),
       last_skipped_packets_warning_ms_(clock_->TimeInMilliseconds()) {
   RTC_DCHECK(owner);
-  if (config.media_send_ssrc) {
-    registered_ssrcs_.insert(*config.media_send_ssrc);
+  if (config.get_local_media_ssrc()) {
+    registered_ssrcs_.insert(*config.get_local_media_ssrc());
   }
   if (config.rtx_send_ssrc) {
     registered_ssrcs_.insert(*config.rtx_send_ssrc);