[media] Fix OpusAudioDecoder::Reset() on PartialAudio tests

This PR (#2501) recreating OpusAUdioDecoder in Reset(). Change to reset a previously initialized state using the #OPUS_RESET_STATE CTL as stated in the opus document.

b/327281974

starboard/shared/opus/opus_audio_decoder.cc

@@ -51,6 +51,9 @@ OpusAudioDecoder::OpusAudioDecoder(const AudioStreamInfo& audio_stream_info)
 }
 
 OpusAudioDecoder::~OpusAudioDecoder() {
+  if (is_valid()) {
+    opus_multistream_decoder_ctl(decoder_, OPUS_RESET_STATE);
+  }
   TeardownCodec();
 }
 
@@ -218,8 +221,9 @@ void OpusAudioDecoder::InitializeCodec() {
 }
 
 void OpusAudioDecoder::TeardownCodec() {
-  if (decoder_) {
+  if (is_valid()) {
     opus_multistream_decoder_destroy(decoder_);
+    decoder_ = NULL;
   }
 }
 
@@ -241,9 +245,19 @@ scoped_refptr<OpusAudioDecoder::DecodedAudio> OpusAudioDecoder::Read(
 void OpusAudioDecoder::Reset() {
   SB_DCHECK(BelongsToCurrentThread());
 
-  TeardownCodec();
-  InitializeCodec();
+  if (is_valid()) {
+    int error = opus_multistream_decoder_ctl(decoder_, OPUS_RESET_STATE);
+    if (error != OPUS_OK) {
+      SB_LOG(ERROR) << "Failed to reset OpusAudioDecoder with error: "
+                    << opus_strerror(error);
+
+      // If fail to reset opus decoder, re-create it.
+      TeardownCodec();
+      InitializeCodec();
+    }
+  }
 
+  frames_per_au_ = kMaxOpusFramesPerAU;
   stream_ended_ = false;
   while (!decoded_audios_.empty()) {
     decoded_audios_.pop();