Don't try to decode more than one EOS at a time.

media/filters/decoder_stream.cc

Index: media/filters/decoder_stream.cc
diff --git a/media/filters/decoder_stream.cc b/media/filters/decoder_stream.cc
index 45172901410c22f0f03977224e00f774fe119afc..de7a23da040109c4ac048b568da19dd458aeb73d 100644
--- a/media/filters/decoder_stream.cc
+++ b/media/filters/decoder_stream.cc
@@ -52,6 +52,7 @@ DecoderStream<StreamType>::DecoderStream(
                                           decoders.Pass(),
                                           set_decryptor_ready_cb)),
       active_splice_(false),
+      decoding_eos_(false),
       pending_decode_requests_(0),
       weak_factory_(this) {}
 
@@ -207,7 +208,7 @@ bool DecoderStream<StreamType>::CanDecodeMore() const {
   // empty.
   int num_decodes =
       static_cast<int>(ready_outputs_.size()) + pending_decode_requests_;
-  return num_decodes < GetMaxDecodeRequests();
+  return !decoding_eos_ && num_decodes < GetMaxDecodeRequests();
 }
 
 template <DemuxerStream::Type StreamType>
@@ -265,6 +266,9 @@ void DecoderStream<StreamType>::Decode(
                               weak_factory_.GetWeakPtr(),
                               buffer_size,
                               buffer->end_of_stream()));
+
+  if (buffer->end_of_stream())

[acolwell GONE FROM CHROMIUM, 2014/08/27 00:44:39]

nit: Shouldn't this be before the Decode() call just in case the callback is
called synchronously inside Decode()?

[sandersd (OOO until July 31), 2014/08/27 01:13:45]

Decode() is defined not to do that, but seems like a good idea.

+    decoding_eos_ = true;
 }
 
 template <DemuxerStream::Type StreamType>
@@ -286,6 +290,9 @@ void DecoderStream<StreamType>::OnDecodeDone(int buffer_size,
 
   TRACE_EVENT_ASYNC_END0("media", GetTraceString<StreamType>(), this);
 
+  if (end_of_stream)
+    decoding_eos_ = false;

[acolwell GONE FROM CHROMIUM, 2014/08/27 00:44:39]

Is there any reason not to simply make this a STATE_ instead of an extra member
variable? It seems like this could be modeled as the state between NORMAL and
END_OF_STREAM.

[sandersd (OOO until July 31), 2014/08/27 01:13:45]

This is true, but I was having trouble proving that change correct when taking
reinitialization (which also sends EOS buffers) and resets into account. It was
conceptually simpler to track the state of the decoder.

I'm willing to take on the task of documenting the whole state machine well
enough to be certain of such changes, if that will be useful to others as well.

[acolwell GONE FROM CHROMIUM, 2014/08/27 01:49:47]

OK. I don't think it is worth holding things up right now. Perhaps file a
cleanup bug and put TODO for documenting the state machine and potentially
removing the decoding_eos_ var.

[sandersd (OOO until July 31), 2014/08/27 21:45:59]

Done.

+
   if (state_ == STATE_ERROR) {
     DCHECK(read_cb_.is_null());
     return;
@@ -447,7 +454,7 @@ void DecoderStream<StreamType>::OnBufferReady(
   Decode(buffer);
 
   // Read more data if the decoder supports multiple parallel decoding requests.
-  if (CanDecodeMore() && !buffer->end_of_stream())
+  if (CanDecodeMore())
     ReadFromDemuxerStream();
 }