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

BUG=webrtc:5805

Review-Url: https://codereview.webrtc.org/2774833003
Cr-Commit-Position: refs/heads/master@{#17391}

webrtc/modules/audio_coding/neteq/decoder_database.cc

@@ -123,6 +123,38 @@ void DecoderDatabase::Reset() {
   active_cng_decoder_type_ = -1;
 }
 
+std::vector<int> DecoderDatabase::SetCodecs(
+    const std::map<int, SdpAudioFormat>& codecs) {
+  // First collect all payload types that we'll remove or reassign, then remove
+  // them from the database.
+  std::vector<int> changed_payload_types;
+  for (const std::pair<uint8_t, const DecoderInfo&> kv : decoders_) {
+    auto i = codecs.find(kv.first);
+    if (i == codecs.end() || i->second != kv.second.GetFormat()) {
+      changed_payload_types.push_back(kv.first);
+    }
+  }
+  for (int pl_type : changed_payload_types) {
+    Remove(pl_type);
+  }
+
+  // Enter the new and changed payload type mappings into the database.
+  for (const auto& kv : codecs) {
+    const int& rtp_payload_type = kv.first;
+    const SdpAudioFormat& audio_format = kv.second;
+    RTC_DCHECK_GE(rtp_payload_type, 0);
+    RTC_DCHECK_LE(rtp_payload_type, 0x7f);
+    if (decoders_.count(rtp_payload_type) == 0) {
+      decoders_.insert(std::make_pair(
+          rtp_payload_type, DecoderInfo(audio_format, decoder_factory_.get())));
+    } else {
+      // The mapping for this payload type hasn't changed.
+    }
+  }
+
+  return changed_payload_types;
+}
+
 int DecoderDatabase::RegisterPayload(uint8_t rtp_payload_type,
                                      NetEqDecoder codec_type,
                                      const std::string& name) {