Delete default_send_ssrc_.

webrtc/media/engine/webrtcvideoengine2.cc

Index: webrtc/media/engine/webrtcvideoengine2.cc
diff --git a/webrtc/media/engine/webrtcvideoengine2.cc b/webrtc/media/engine/webrtcvideoengine2.cc
index e34056d905257371b6f9c0db015f38a3bdcf3a85..45d8f5ece2b2da8ff2673764419ff7fe94dee0c8 100644
--- a/webrtc/media/engine/webrtcvideoengine2.cc
+++ b/webrtc/media/engine/webrtcvideoengine2.cc
@@ -619,7 +619,6 @@ WebRtcVideoChannel2::WebRtcVideoChannel2(
 
   rtcp_receiver_report_ssrc_ = kDefaultRtcpReceiverReportSsrc;
   sending_ = false;
-  default_send_ssrc_ = 0;
   RTC_DCHECK(ValidateCodecFormats(recv_codecs));
   recv_codecs_ = FilterSupportedCodecs(MapCodecs(recv_codecs));
 }
@@ -1030,9 +1029,6 @@ bool WebRtcVideoChannel2::AddSendStream(const StreamParams& sp) {
     for (auto& kv : receive_streams_)
       kv.second->SetLocalSsrc(ssrc);
   }
-  if (default_send_ssrc_ == 0) {
-    default_send_ssrc_ = ssrc;
-  }
   if (sending_) {
     stream->Start();
   }
@@ -1043,15 +1039,8 @@ bool WebRtcVideoChannel2::AddSendStream(const StreamParams& sp) {
 bool WebRtcVideoChannel2::RemoveSendStream(uint32_t ssrc) {
   LOG(LS_INFO) << "RemoveSendStream: " << ssrc;
 
-  if (ssrc == 0) {
-    if (default_send_ssrc_ == 0) {
-      LOG(LS_ERROR) << "No default send stream active.";
-      return false;
-    }
-
-    LOG(LS_VERBOSE) << "Removing default stream: " << default_send_ssrc_;
-    ssrc = default_send_ssrc_;
-  }
+  // TODO(nisse): Allow no ssrc? Used to mean default ssrc.
+  RTC_CHECK(ssrc != 0);

[pthatcher1, 2016/03/18 16:55:48]

Technically, 0 is a valid SSRC.  We were using it as a special value before, but
that was technically incorrect.  If we've fixed that now, I see no reason to not
allow SSRC 0 to be used.

[pbos-webrtc, 2016/03/20 21:19:19]

I think it might hit some DCHECKs lower.

[nisse-webrtc, 2016/03/21 07:53:53]

I don't think ssrc == 0 works yet. There are RTC_DCHECKs in AddSendStream and
AddRecvStream, and 0 is handled specially by default_unsignalled_ssrc handler.

We should never have RTC_DCHECK crash on invalid values provided by the peer.
Not sure if that can happen here (where are ssrc:s allocated?), but it makes
some sense to keep the a check here to match the check in AddSendStream. But
should change to RTC_DCHECK to really match that one.

 
   WebRtcVideoSendStream* removed_stream;
   {
@@ -1084,10 +1073,6 @@ bool WebRtcVideoChannel2::RemoveSendStream(uint32_t ssrc) {
 
   delete removed_stream;
 
-  if (ssrc == default_send_ssrc_) {
-    default_send_ssrc_ = 0;
-  }
-
   return true;
 }