Add support for cancellation of demuxer reads.

media/filters/blocking_url_protocol.cc

 // 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.
 
 #include "media/filters/blocking_url_protocol.h"
 
 #include <stddef.h>
 
 #include "base/bind.h"
 #include "base/macros.h"
@@ skipping 44 matching lines @@
 
   if (events[index] == &aborted_)
     return AVERROR(EIO);
 
   if (last_read_bytes_ == DataSource::kReadError) {
     aborted_.Signal();
     error_cb_.Run();
     return AVERROR(EIO);
   }
 
+  if (last_read_bytes_ == DataSource::kAborted)
+    return AVERROR(EIO);
+
   read_position_ += last_read_bytes_;
   return last_read_bytes_;
 }
 
 bool BlockingUrlProtocol::GetPosition(int64_t* position_out) {
   *position_out = read_position_;
   return true;
 }
 
 bool BlockingUrlProtocol::SetPosition(int64_t position) {
@@ skipping 14 matching lines @@
 bool BlockingUrlProtocol::IsStreaming() {
   return data_source_->IsStreaming();
 }
 
 void BlockingUrlProtocol::SignalReadCompleted(int size) {
   last_read_bytes_ = size;
   read_complete_.Signal();
 }
 
 }  // namespace media