AcmReceiver: Eliminate AcmReceiver::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 952ab238ebb9616cc1d87d6076a0f9c1ae7aa679..98bb37cf1f543e04db4befb2e880871632eee7b4 100644
--- a/webrtc/modules/audio_coding/neteq/include/neteq.h
+++ b/webrtc/modules/audio_coding/neteq/include/neteq.h
@@ -259,6 +259,11 @@ class NetEq {
   // value if we have no decoder for that payload type.
   virtual rtc::Optional<CodecInst> GetDecoder(int payload_type) const = 0;
 
+  // Returns the decoder format for the given payload type. Returns null if no
+  // such payload type was registered, or if it was registered without
+  // providing an SdpAudioFormat.
+  virtual const SdpAudioFormat* GetDecoderFormat(int payload_type) const = 0;
+
   // Not implemented.
   virtual int SetTargetNumberOfChannels() = 0;