Add encoder/decoder names to software H264.

webrtc/modules/video_coding/codecs/h264/h264_decoder_impl.h

Index: webrtc/modules/video_coding/codecs/h264/h264_decoder_impl.h
diff --git a/webrtc/modules/video_coding/codecs/h264/h264_decoder_impl.h b/webrtc/modules/video_coding/codecs/h264/h264_decoder_impl.h
index e724c371c8198c3ea56feed98b9d376b813dc730..fc730a4f4d898aa81efca9ca18f1b20d7237fbfb 100644
--- a/webrtc/modules/video_coding/codecs/h264/h264_decoder_impl.h
+++ b/webrtc/modules/video_coding/codecs/h264/h264_decoder_impl.h
@@ -52,6 +52,8 @@ class H264DecoderImpl : public H264Decoder {
                  const CodecSpecificInfo* codec_specific_info = nullptr,
                  int64_t render_time_ms = -1) override;
 
+  const char* ImplementationName() const override;
+
  private:
   // Called by FFmpeg when it needs a frame buffer to store decoded frames in.
   // The |VideoFrame| returned by FFmpeg at |Decode| originate from here. Their