NetEq: Ask AudioDecoder for sample rate instead of passing it as an argument

webrtc/modules/audio_coding/acm2/acm_receiver.cc

Index: webrtc/modules/audio_coding/acm2/acm_receiver.cc
diff --git a/webrtc/modules/audio_coding/acm2/acm_receiver.cc b/webrtc/modules/audio_coding/acm2/acm_receiver.cc
index c15239f0f3e73aa25cdb7484d8a5bf367aeda0a4..bad484cda434bd24880e27c5fbff547f35697c42 100644
--- a/webrtc/modules/audio_coding/acm2/acm_receiver.cc
+++ b/webrtc/modules/audio_coding/acm2/acm_receiver.cc
@@ -242,7 +242,7 @@ int32_t AcmReceiver::AddCodec(int acm_codec_id,
     ret_val = neteq_->RegisterPayloadType(neteq_decoder, name, payload_type);
   } else {
     ret_val = neteq_->RegisterExternalDecoder(
-        audio_decoder, neteq_decoder, name, payload_type, sample_rate_hz);
+        audio_decoder, neteq_decoder, name, payload_type);
   }
   if (ret_val != NetEq::kOK) {
     LOG(LERROR) << "AcmReceiver::AddCodec " << acm_codec_id