Move VideoDecoder::Create() logic to separate internal video decoder factory

webrtc/media/engine/videodecodersoftwarefallbackwrapper.h

 /*
  *  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 28 matching lines @@
       DecodedImageCallback* callback) override;
 
   int32_t Release() override;
   bool PrefersLateDecoding() const override;
 
   const char* ImplementationName() const override;
 
  private:
   bool InitFallbackDecoder();
 
-  const DecoderType decoder_type_;
+  const VideoCodecType codec_type_;
   VideoDecoder* const decoder_;
 
   VideoCodec codec_settings_;
   int32_t number_of_cores_;
   std::string fallback_implementation_name_;
   std::unique_ptr<VideoDecoder> fallback_decoder_;
   DecodedImageCallback* callback_;
 };
 
 }  // namespace webrtc
 
 #endif  // WEBRTC_MEDIA_ENGINE_VIDEODECODERSOFTWAREFALLBACKWRAPPER_H_