media: Discard the previous decoder immediately on fallback

media/filters/decoder_stream.h

Index: media/filters/decoder_stream.h
diff --git a/media/filters/decoder_stream.h b/media/filters/decoder_stream.h
index e0f26c97c1ec2c6580e5f62c994b6f10d5fa2085..28a11ebccc6644dfae8fd6950b9d05d1a8924b65 100644
--- a/media/filters/decoder_stream.h
+++ b/media/filters/decoder_stream.h
@@ -112,10 +112,6 @@ class MEDIA_EXPORT DecoderStream {
     config_change_observer_cb_ = config_change_observer;
   }
 
-  const Decoder* get_previous_decoder_for_testing() const {
-    return previous_decoder_.get();
-  }
-
   int get_pending_buffers_size_for_testing() const {
     return pending_buffers_.size();
   }
@@ -205,12 +201,8 @@ class MEDIA_EXPORT DecoderStream {
 
   std::unique_ptr<Decoder> decoder_;
 
-  // When falling back from H/W decoding to S/W decoding, destructing the
-  // GpuVideoDecoder too early results in black frames being displayed.
-  // |previous_decoder_| is used to keep it alive.  It is destroyed once we've
-  // decoded at least media::limits::kMaxVideoFrames frames after fallback.
-  int decoded_frames_since_fallback_;
-  std::unique_ptr<Decoder> previous_decoder_;
+  // Whether |decoder_| has produced a frame yet. Reset on fallback.
+  bool decoder_produced_a_frame_;
 
   std::unique_ptr<DecryptingDemuxerStream> decrypting_demuxer_stream_;