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

webrtc/video_decoder.h

Index: webrtc/video_decoder.h
diff --git a/webrtc/video_decoder.h b/webrtc/video_decoder.h
index 8c89ce97717c76a269a4b32ff0f4fa7cf14d2a75..b8d2c96b1be8da1cb27138f0550302ebe7b378c1 100644
--- a/webrtc/video_decoder.h
+++ b/webrtc/video_decoder.h
@@ -50,15 +50,6 @@ class DecodedImageCallback {
 
 class VideoDecoder {
  public:
-  enum DecoderType {
-    kH264,
-    kVp8,
-    kVp9,
-    kUnsupportedCodec,
-  };
-
-  static VideoDecoder* Create(DecoderType codec_type);
-
   virtual ~VideoDecoder() {}
 
   virtual int32_t InitDecode(const VideoCodec* codec_settings,
@@ -83,29 +74,6 @@ class VideoDecoder {
   virtual const char* ImplementationName() const { return "unknown"; }
 };
 
-// Video decoder class to be used for unknown codecs. Doesn't support decoding
-// but logs messages to LS_ERROR.
-class NullVideoDecoder : public VideoDecoder {
- public:
-  NullVideoDecoder();
-
-  int32_t InitDecode(const VideoCodec* codec_settings,
-                     int32_t number_of_cores) override;
-
-  int32_t Decode(const EncodedImage& input_image,
-                 bool missing_frames,
-                 const RTPFragmentationHeader* fragmentation,
-                 const CodecSpecificInfo* codec_specific_info,
-                 int64_t render_time_ms) override;
-
-  int32_t RegisterDecodeCompleteCallback(
-      DecodedImageCallback* callback) override;
-
-  int32_t Release() override;
-
-  const char* ImplementationName() const override;
-};
-
 }  // namespace webrtc
 
 #endif  // WEBRTC_VIDEO_DECODER_H_