Add support for cancellation of demuxer reads.

media/filters/ffmpeg_demuxer.h

 // Copyright (c) 2012 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 // Implements the Demuxer interface using FFmpeg's libavformat.  At this time
 // will support demuxing any audio/video format thrown at it.  The streams
 // output mime types audio/x-ffmpeg and video/x-ffmpeg and include an integer
 // key FFmpegCodecID which contains the CodecID enumeration value.  The CodecIDs
 // can be used to create and initialize the corresponding FFmpeg decoder.
 //
@@ skipping 68 matching lines @@
   // Enters the end of stream state. After delivering remaining queued buffers
   // only end of stream buffers will be delivered.
   void SetEndOfStream();
 
   // Drops queued buffers and clears end of stream state.
   void FlushBuffers();
 
   // Empties the queues and ignores any additional calls to Read().
   void Stop();
 
+  // Aborts any pending reads.
+  void Abort();
+
   base::TimeDelta duration() const { return duration_; }
 
   // Enables fixes for files with negative timestamps.  Normally all timestamps
   // are rebased against FFmpegDemuxer::start_time() whenever that value is
   // negative.  When this fix is enabled, only AUDIO stream packets will be
   // rebased to time zero, all other stream types will use the muxed timestamp.
   //
   // Further, when no codec delay is present, all AUDIO packets which originally
   // had negative timestamps will be marked for post-decode discard.  When codec
   // delay is present, it is assumed the decoder will handle discard and does
@@ skipping 105 matching lines @@
                 const EncryptedMediaInitDataCB& encrypted_media_init_data_cb,
                 const MediaTracksUpdatedCB& media_tracks_updated_cb,
                 const scoped_refptr<MediaLog>& media_log);
   ~FFmpegDemuxer() override;
 
   // Demuxer implementation.
   std::string GetDisplayName() const override;
   void Initialize(DemuxerHost* host,
                   const PipelineStatusCB& status_cb,
                   bool enable_text_tracks) override;
+  void AbortPendingReads() override;
   void Stop() override;
   void StartWaitingForSeek(base::TimeDelta seek_time) override;
   void CancelPendingSeek(base::TimeDelta seek_time) override;
   void Seek(base::TimeDelta time, const PipelineStatusCB& cb) override;
   base::Time GetTimelineOffset() const override;
   DemuxerStream* GetStream(DemuxerStream::Type type) override;
   base::TimeDelta GetStartTime() const override;
   int64_t GetMemoryUsage() const override;
 
   // Calls |encrypted_media_init_data_cb_| with the initialization data
@@ skipping 19 matching lines @@
 
  private:
   // To allow tests access to privates.
   friend class FFmpegDemuxerTest;
 
   // FFmpeg callbacks during initialization.
   void OnOpenContextDone(const PipelineStatusCB& status_cb, bool result);
   void OnFindStreamInfoDone(const PipelineStatusCB& status_cb, int result);
 
   // FFmpeg callbacks during seeking.
-  void OnSeekFrameDone(const PipelineStatusCB& cb, int result);
+  void OnSeekFrameDone(int result);
 
   // FFmpeg callbacks during reading + helper method to initiate reads.
   void ReadFrameIfNeeded();
   void OnReadFrameDone(ScopedAVPacket packet, int result);
 
   // Returns true iff any stream has additional capacity. Note that streams can
   // go over capacity depending on how the file is muxed.
   bool StreamsHaveAvailableCapacity();
 
   // Returns true if the maximum allowed memory usage has been reached.
@@ skipping 23 matching lines @@
   base::Thread blocking_thread_;
 
   // Tracks if there's an outstanding av_read_frame() operation.
   //
   // TODO(scherkus): Allow more than one read in flight for higher read
   // throughput using demuxer_bench to verify improvements.
   bool pending_read_;
 
   // Tracks if there's an outstanding av_seek_frame() operation. Used to discard
   // results of pre-seek av_read_frame() operations.
-  bool pending_seek_;
+  PipelineStatusCB pending_seek_cb_;
 
   // |streams_| mirrors the AVStream array in AVFormatContext. It contains
   // FFmpegDemuxerStreams encapsluating AVStream objects at the same index.
   //
   // Since we only support a single audio and video stream, |streams_| will
   // contain NULL entries for additional audio/video streams as well as for
   // stream types that we do not currently support.
   //
   // Once initialized, operations on FFmpegDemuxerStreams should be carried out
   // on the demuxer thread.
@@ skipping 43 matching lines @@
 
   // NOTE: Weak pointers must be invalidated before all other member variables.
   base::WeakPtrFactory<FFmpegDemuxer> weak_factory_;
 
   DISALLOW_COPY_AND_ASSIGN(FFmpegDemuxer);
 };
 
 }  // namespace media
 
 #endif  // MEDIA_FILTERS_FFMPEG_DEMUXER_H_