Fix crash when registering abs-send-time to AudioSend/ReceiveStream.

webrtc/audio/audio_send_stream.cc

Index: webrtc/audio/audio_send_stream.cc
diff --git a/webrtc/audio/audio_send_stream.cc b/webrtc/audio/audio_send_stream.cc
index 39066720cb3201bd098d5686b7c2c20c7ab7e0f2..ad6366bc8095deebe830b33c9115cf77afe83adf 100644
--- a/webrtc/audio/audio_send_stream.cc
+++ b/webrtc/audio/audio_send_stream.cc
@@ -79,6 +79,9 @@ AudioSendStream::AudioSendStream(
       channel_proxy_->SetSendAudioLevelIndicationStatus(true, extension.id);
     } else if (extension.uri == RtpExtension::kTransportSequenceNumberUri) {
       channel_proxy_->EnableSendTransportSequenceNumber(extension.id);
+    } else if (extension.uri == RtpExtension::kAbsSendTimeUri) {
+      LOG(LS_WARNING) << RtpExtension::kAbsSendTimeUri
+                      << " is no longer supported for audio.";
     } else {
       RTC_NOTREACHED() << "Registering unsupported RTP extension.";
     }