Add support for cancellation of demuxer reads.

media/filters/memory_data_source.cc

 // 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.
 
 #include "media/filters/memory_data_source.h"
 
 #include <algorithm>
 
 #include "base/logging.h"
 
@@ skipping 25 matching lines @@
     memcpy(data, data_ + position, clamped_size);
   }
 
   read_cb.Run(clamped_size);
 }
 
 void MemoryDataSource::Stop() {
   is_stopped_ = true;
 }
 
+void MemoryDataSource::Abort() {}
+
 bool MemoryDataSource::GetSize(int64_t* size_out) {
   *size_out = size_;
   return true;
 }
 
 bool MemoryDataSource::IsStreaming() {
   return false;
 }
 
 void MemoryDataSource::SetBitrate(int bitrate) {}
 
 }  // namespace media