AcmReceiver: Look up last decoder in NetEq's table of decoders

webrtc/modules/audio_coding/neteq/include/neteq.h

Index: webrtc/modules/audio_coding/neteq/include/neteq.h
diff --git a/webrtc/modules/audio_coding/neteq/include/neteq.h b/webrtc/modules/audio_coding/neteq/include/neteq.h
index cae56b386273c56fe00385d841fa3fa5849886cb..22d994e3aa987b0358ba086da2fffcd8c18c5cc6 100644
--- a/webrtc/modules/audio_coding/neteq/include/neteq.h
+++ b/webrtc/modules/audio_coding/neteq/include/neteq.h
@@ -252,6 +252,10 @@ class NetEq {
   // (Config::sample_rate_hz) is returned.
   virtual int last_output_sample_rate_hz() const = 0;
 
+  // Returns info about the decoder for the given payload type, or an empty
+  // value if we have no decoder for that payload type.
+  virtual rtc::Optional<CodecInst> GetDecoder(int payload_type) const = 0;
+
   // Not implemented.
   virtual int SetTargetNumberOfChannels() = 0;