Add support for cancellation of demuxer reads.

media/filters/memory_data_source.h

 // Copyright 2016 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.
 
 #ifndef MEDIA_FILTERS_MEMORY_DATA_SOURCE_H_
 #define MEDIA_FILTERS_MEMORY_DATA_SOURCE_H_
 
 #include <stdint.h>
 
 #include "base/macros.h"
 #include "media/base/data_source.h"
 
 namespace media {
 
 // Basic data source that treats the URL as a file path, and uses the file
 // system to read data for a media pipeline.
 class MEDIA_EXPORT MemoryDataSource : public DataSource {
  public:
   // Construct MemoryDataSource with |data| and |size|. The data is guaranteed
   // to be valid during the lifetime of MemoryDataSource.
   MemoryDataSource(const uint8_t* data, size_t size);
   ~MemoryDataSource() final;
 
   // Implementation of DataSource.
   void Read(int64_t position,
             int size,
             uint8_t* data,
             const DataSource::ReadCB& read_cb) final;
   void Stop() final;
+  void Abort() final;
   bool GetSize(int64_t* size_out) final;
   bool IsStreaming() final;
   void SetBitrate(int bitrate) final;
 
  private:
   const uint8_t* data_ = nullptr;
   size_t size_ = 0;
 
   bool is_stopped_ = false;
 
   DISALLOW_COPY_AND_ASSIGN(MemoryDataSource);
 };
 
 }  // namespace media
 
 #endif  // MEDIA_FILTERS_MEMORY_DATA_SOURCE_H_