Reland "WebRtcVoiceMediaChannel::AddRecvStream: Don't call SetRecPayloadType"

BUG=webrtc:5805

Review-Url: https://codereview.webrtc.org/2774833003
Cr-Commit-Position: refs/heads/master@{#17391}
diff --git a/webrtc/modules/audio_coding/neteq/neteq_impl.cc b/webrtc/modules/audio_coding/neteq/neteq_impl.cc
index 5015b7e..501e567 100644
--- a/webrtc/modules/audio_coding/neteq/neteq_impl.cc
+++ b/webrtc/modules/audio_coding/neteq/neteq_impl.cc
@@ -212,6 +212,15 @@
   return kOK;
 }
 
+void NetEqImpl::SetCodecs(const std::map<int, SdpAudioFormat>& codecs) {
+  rtc::CritScope lock(&crit_sect_);
+  const std::vector<int> changed_payload_types =
+      decoder_database_->SetCodecs(codecs);
+  for (const int pt : changed_payload_types) {
+    packet_buffer_->DiscardPacketsWithPayloadType(pt);
+  }
+}
+
 int NetEqImpl::RegisterPayloadType(NetEqDecoder codec,
                                    const std::string& name,
                                    uint8_t rtp_payload_type) {