Revert of Opus implementation of the AudioDecoderFactoryTemplate API

webrtc/modules/audio_coding/codecs/builtin_audio_decoder_factory_internal.cc

 /*
  *  Copyright (c) 2016 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 144 matching lines @@
              return rtc::Optional<int>(2);
            } else {
              return rtc::Optional<int>();  // Bad stereo parameter.
            }
          }
          return rtc::Optional<int>(1);  // Default to mono.
        }();
        if (format.clockrate_hz == 48000 && format.num_channels == 2 &&
            num_channels) {
          if (out) {
-           out->reset(new AudioDecoderOpusImpl(*num_channels));
+           out->reset(new AudioDecoderOpus(*num_channels));
          }
          return true;
        } else {
          return false;
        }
      }},
 #endif
 };
 
 class BuiltinAudioDecoderFactory : public AudioDecoderFactory {
@@ skipping 72 matching lines @@
 
 }  // namespace
 
 rtc::scoped_refptr<AudioDecoderFactory>
 CreateBuiltinAudioDecoderFactoryInternal() {
   return rtc::scoped_refptr<AudioDecoderFactory>(
       new rtc::RefCountedObject<BuiltinAudioDecoderFactory>);
 }
 
 }  // namespace webrtc