Attempt decoder fallback when the first decode call fails.

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 4b03587253fa06cccd378d527ddf8f1de8e7ff5a..26e9790f520e40855baf18506259402b214b4917 100644
--- a/media/filters/decoder_stream.cc
+++ b/media/filters/decoder_stream.cc
@@ -59,6 +59,7 @@ DecoderStream<StreamType>::DecoderStream(
       decoding_eos_(false),
       pending_decode_requests_(0),
       duration_tracker_(8),
+      sequence_token_(0),
       weak_factory_(this) {}
 
 template <DemuxerStream::Type StreamType>
@@ -253,6 +254,7 @@ void DecoderStream<StreamType>::OnDecoderSelected(
     DCHECK(decoder_);
   }
 
+  ++sequence_token_;
   previous_decoder_ = std::move(decoder_);
   decoded_frames_since_fallback_ = 0;
   decoder_ = std::move(selected_decoder);
@@ -319,12 +321,14 @@ void DecoderStream<StreamType>::Decode(
   else if (buffer->duration() != kNoTimestamp())
     duration_tracker_.AddSample(buffer->duration());
 
+  if (!decoded_frames_since_fallback_ && !previous_decoder_)
+    pending_buffers_.push_back(buffer);
+
   ++pending_decode_requests_;
   decoder_->Decode(buffer,
                    base::Bind(&DecoderStream<StreamType>::OnDecodeDone,
-                              weak_factory_.GetWeakPtr(),
-                              buffer_size,
-                              buffer->end_of_stream()));
+                              weak_factory_.GetWeakPtr(), sequence_token_,
+                              buffer_size, buffer->end_of_stream()));
 }
 
 template <DemuxerStream::Type StreamType>
@@ -333,10 +337,15 @@ void DecoderStream<StreamType>::FlushDecoder() {
 }
 
 template <DemuxerStream::Type StreamType>
-void DecoderStream<StreamType>::OnDecodeDone(int buffer_size,
+void DecoderStream<StreamType>::OnDecodeDone(int sequence_token,
+                                             int buffer_size,
                                              bool end_of_stream,
                                              typename Decoder::Status status) {
   FUNCTION_DVLOG(2) << ": " << status;
+  // Ignore stale calls from a previous decoder.
+  if (sequence_token_ != sequence_token)
+    return;
+
   DCHECK(state_ == STATE_NORMAL || state_ == STATE_FLUSHING_DECODER ||
          state_ == STATE_PENDING_DEMUXER_READ || state_ == STATE_ERROR)
       << state_;
@@ -363,6 +372,19 @@ void DecoderStream<StreamType>::OnDecodeDone(int buffer_size,
 
   switch (status) {
     case Decoder::kDecodeError:
+      if (!decoded_frames_since_fallback_) {
+        pending_decode_requests_ = 0;
+        state_ = STATE_REINITIALIZING_DECODER;
+        decoder_selector_->SelectDecoder(
+            stream_, nullptr,
+            base::Bind(&DecoderStream<StreamType>::OnDecoderSelected,
+                       weak_factory_.GetWeakPtr()),
+            base::Bind(&DecoderStream<StreamType>::OnDecodeOutputReady,
+                       weak_factory_.GetWeakPtr()),
+            waiting_for_decryption_key_cb_);
+        return;
+      }
+
       state_ = STATE_ERROR;
       MEDIA_LOG(ERROR, media_log_) << GetStreamTypeString() << " decode error";
       ready_outputs_.clear();
@@ -430,8 +452,8 @@ void DecoderStream<StreamType>::OnDecodeOutputReady(
 
   // Destruct any previous decoder once we've decoded enough frames to ensure
   // that it's no longer in use.
-  if (previous_decoder_ &&
-      ++decoded_frames_since_fallback_ > limits::kMaxVideoFrames) {
+  if (++decoded_frames_since_fallback_ > limits::kMaxVideoFrames &&
+      previous_decoder_) {
     previous_decoder_.reset();
   }
 }
@@ -443,6 +465,13 @@ void DecoderStream<StreamType>::ReadFromDemuxerStream() {
   DCHECK(CanDecodeMore());
   DCHECK(reset_cb_.is_null());
 
+  if (!pending_buffers_.empty() && previous_decoder_) {
+    scoped_refptr<DecoderBuffer> buffer = pending_buffers_.front();
+    pending_buffers_.pop_front();
+    Decode(buffer);
+    return;
+  }
+
   state_ = STATE_PENDING_DEMUXER_READ;
   stream_->Read(base::Bind(&DecoderStream<StreamType>::OnBufferReady,
                            weak_factory_.GetWeakPtr()));