Turned AudioDecoderFactory into a RefCounted thing to use with scoped_refptr.

webrtc/modules/audio_coding/codecs/builtin_audio_decoder_factory.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 127 matching lines @@
       if (STR_CASE_CMP(format.name.c_str(), dc.name) == 0) {
         return std::unique_ptr<AudioDecoder>(dc.constructor(format));
       }
     }
     return nullptr;
   }
 };
 
 }  // namespace
 
-std::unique_ptr<AudioDecoderFactory> CreateBuiltinAudioDecoderFactory() {
-  return std::unique_ptr<AudioDecoderFactory>(new BuiltinAudioDecoderFactory);
+rtc::scoped_refptr<AudioDecoderFactory> CreateBuiltinAudioDecoderFactory() {
+  return rtc::scoped_refptr<AudioDecoderFactory>(
+      new rtc::RefCountedObject<BuiltinAudioDecoderFactory>);
 }
 
 }  // namespace webrtc