Revert of Opus implementation of the AudioDecoderFactoryTemplate API

webrtc/test/fuzzers/audio_decoder_opus_fuzzer.cc

Index: webrtc/test/fuzzers/audio_decoder_opus_fuzzer.cc
diff --git a/webrtc/test/fuzzers/audio_decoder_opus_fuzzer.cc b/webrtc/test/fuzzers/audio_decoder_opus_fuzzer.cc
index 23b65a64626b2aca7cbda65275f67aec0ac8e02d..ee9f591aca6b82ae39c43673495c1bcc4a191f67 100644
--- a/webrtc/test/fuzzers/audio_decoder_opus_fuzzer.cc
+++ b/webrtc/test/fuzzers/audio_decoder_opus_fuzzer.cc
@@ -14,7 +14,7 @@
 namespace webrtc {
 void FuzzOneInput(const uint8_t* data, size_t size) {
   const size_t channels = (size % 2) + 1;  // 1 or 2 channels.
-  AudioDecoderOpusImpl dec(channels);
+  AudioDecoderOpus dec(channels);
   const int kSampleRateHz = 48000;
   const size_t kAllocatedOuputSizeSamples = kSampleRateHz / 10;  // 100 ms.
   int16_t output[kAllocatedOuputSizeSamples];