NetEq: Use a BuiltinAudioDecoderFactory to create decoders

webrtc/modules/audio_coding/neteq/audio_decoder_impl.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 14 matching lines @@
 namespace webrtc {
 
 using NetEqDecoder = acm2::RentACodec::NetEqDecoder;
 
 // Returns true if |codec_type| is supported.
 bool CodecSupported(NetEqDecoder codec_type);
 
 // Returns the sample rate for |codec_type|.
 int CodecSampleRateHz(NetEqDecoder codec_type);
 
-// Creates an AudioDecoder object of type |codec_type|. Returns NULL for for
-// unsupported codecs, and when creating an AudioDecoder is not applicable
-// (e.g., for RED and DTMF/AVT types).
-AudioDecoder* CreateAudioDecoder(NetEqDecoder codec_type);
-
 }  // namespace webrtc
 #endif  // WEBRTC_MODULES_AUDIO_CODING_NETEQ_AUDIO_DECODER_IMPL_H_