Revert of Opus implementation of the AudioDecoderFactoryTemplate API

webrtc/modules/audio_coding/codecs/opus/audio_decoder_opus.h

Index: webrtc/modules/audio_coding/codecs/opus/audio_decoder_opus.h
diff --git a/webrtc/modules/audio_coding/codecs/opus/audio_decoder_opus.h b/webrtc/modules/audio_coding/codecs/opus/audio_decoder_opus.h
index dcdaf9281ecbe5c59088c13583ed4a95c6f2cab6..e848f37466d8e6eda2072ca0d4202fcab634aafd 100644
--- a/webrtc/modules/audio_coding/codecs/opus/audio_decoder_opus.h
+++ b/webrtc/modules/audio_coding/codecs/opus/audio_decoder_opus.h
@@ -17,10 +17,10 @@
 
 namespace webrtc {
 
-class AudioDecoderOpusImpl final : public AudioDecoder {
+class AudioDecoderOpus final : public AudioDecoder {
  public:
-  explicit AudioDecoderOpusImpl(size_t num_channels);
-  ~AudioDecoderOpusImpl() override;
+  explicit AudioDecoderOpus(size_t num_channels);
+  ~AudioDecoderOpus() override;
 
   std::vector<ParseResult> ParsePayload(rtc::Buffer&& payload,
                                         uint32_t timestamp) override;
@@ -47,7 +47,7 @@
  private:
   OpusDecInst* dec_state_;
   const size_t channels_;
-  RTC_DISALLOW_COPY_AND_ASSIGN(AudioDecoderOpusImpl);
+  RTC_DISALLOW_COPY_AND_ASSIGN(AudioDecoderOpus);
 };
 
 }  // namespace webrtc