Adding audio network adaptor to AudioEncoderOpus.

webrtc/modules/audio_coding/codecs/audio_encoder.cc

Index: webrtc/modules/audio_coding/codecs/audio_encoder.cc
diff --git a/webrtc/modules/audio_coding/codecs/audio_encoder.cc b/webrtc/modules/audio_coding/codecs/audio_encoder.cc
index c433dcdd0f1c9613cb7a9be44bf28d3f06237185..f7855ac2a4e961cf686d2527f144542a37a0246c 100644
--- a/webrtc/modules/audio_coding/codecs/audio_encoder.cc
+++ b/webrtc/modules/audio_coding/codecs/audio_encoder.cc
@@ -67,4 +67,12 @@ void AudioEncoder::SetTargetBitrate(int target_bps) {}
 rtc::ArrayView<std::unique_ptr<AudioEncoder>>
 AudioEncoder::ReclaimContainedEncoders() { return nullptr; }
 
+void AudioEncoder::OnReceivedUplinkBandwidth(int uplink_bandwidth_bps) {}
+
+void AudioEncoder::OnReceivedUplinkPacketLossFraction(float uplink_packet_loss_fraction) {}
+
+void AudioEncoder::OnReceivedTargetAudioBitrate(int target_audio_bitrate_bps) {}
+
+void AudioEncoder::OnReceivedRtt(int rtt_ms) {}
+
 }  // namespace webrtc