Forward the SignalFirstPacketReceived to RtpReceiver.

webrtc/api/webrtcsession.cc

Index: webrtc/api/webrtcsession.cc
diff --git a/webrtc/api/webrtcsession.cc b/webrtc/api/webrtcsession.cc
index 80352cf83246f3ff5f42a4bfa4be64f496a5e153..8d86abecc50d9eb327e97a5ef1c250315c874319 100644
--- a/webrtc/api/webrtcsession.cc
+++ b/webrtc/api/webrtcsession.cc
@@ -1817,6 +1817,8 @@ bool WebRtcSession::CreateVoiceChannel(const cricket::ContentInfo* content,
 
   voice_channel_->SignalDtlsSetupFailure.connect(
       this, &WebRtcSession::OnDtlsSetupFailure);
+  voice_channel_->SignalFirstPacketReceived.connect(
+      this, &WebRtcSession::OnChannelFirstPacketReceived);
 
   SignalVoiceChannelCreated();
   voice_channel_->SignalSentPacket.connect(this,
@@ -1840,6 +1842,8 @@ bool WebRtcSession::CreateVideoChannel(const cricket::ContentInfo* content,
   }
   video_channel_->SignalDtlsSetupFailure.connect(
       this, &WebRtcSession::OnDtlsSetupFailure);
+  video_channel_->SignalFirstPacketReceived.connect(
+      this, &WebRtcSession::OnChannelFirstPacketReceived);
 
   SignalVideoChannelCreated();
   video_channel_->SignalSentPacket.connect(this,
@@ -1881,6 +1885,21 @@ void WebRtcSession::OnDtlsSetupFailure(cricket::BaseChannel*, bool rtcp) {
            rtcp ? kDtlsSetupFailureRtcp : kDtlsSetupFailureRtp);
 }
 
+void WebRtcSession::OnChannelFirstPacketReceived(
+    cricket::BaseChannel* channel) {
+  ASSERT(signaling_thread()->IsCurrent());
+
+  if (!has_received_audio_packet_ &&
+      channel->MediaType() == cricket::MEDIA_TYPE_AUDIO) {
+    has_received_audio_packet_ = true;

[pthatcher1, 2016/06/08 17:35:55]

To be consistent with naming, might as well call it
received_first_audio_packet_.

[Zhi Huang, 2016/06/09 00:37:36]

Done.

+    SignalFirstAudioPacketReceived();
+  } else if (!has_received_video_packet_ &&
+             channel->MediaType() == cricket::MEDIA_TYPE_VIDEO) {
+    has_received_video_packet_ = true;
+    SignalFirstVideoPacketReceived();
+  }
+}
+
 void WebRtcSession::OnDataChannelMessageReceived(
     cricket::DataChannel* channel,
     const cricket::ReceiveDataParams& params,