Stopped using the NetEqDecoder enum internally in NetEq.

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

 /*
  *  Copyright (c) 2012 The WebRTC project authors. All Rights Reserved.
  *
  *  Use of this source code is governed by a BSD-style license
  *  that can be found in the LICENSE file in the root of the source
  *  tree. An additional intellectual property rights grant can be found
  *  in the file PATENTS.  All contributing project authors may
  *  be found in the AUTHORS file in the root of the source tree.
  */
 
@@ skipping 240 matching lines @@
 
   // Returns the sample rate in Hz of the audio produced in the last GetAudio
   // call. If GetAudio has not been called yet, the configured sample rate
   // (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;
 
-  // 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;
+  // Returns the decoder format for the given payload type. Returns empty if no
+  // such payload type was registered.
+  virtual rtc::Optional<SdpAudioFormat> GetDecoderFormat(
+      int payload_type) const = 0;
 
   // Not implemented.
   virtual int SetTargetNumberOfChannels() = 0;
 
   // Not implemented.
   virtual int SetTargetSampleRate() = 0;
 
   // Returns the error code for the last occurred error. If no error has
   // occurred, 0 is returned.
   virtual int LastError() const = 0;
@@ skipping 24 matching lines @@
 
  protected:
   NetEq() {}
 
  private:
   RTC_DISALLOW_COPY_AND_ASSIGN(NetEq);
 };
 
 }  // namespace webrtc
 #endif  // WEBRTC_MODULES_AUDIO_CODING_NETEQ_INCLUDE_NETEQ_H_