Add Resource Handler for creating Streams to forward to extensions

content/browser/streams/stream_write_observer.h

 // Copyright (c) 2013 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 CONTENT_BROWSER_STREAMS_STREAM_WRITE_OBSERVER_H_
 #define CONTENT_BROWSER_STREAMS_STREAM_WRITE_OBSERVER_H_
 
 namespace content {
 
 class Stream;
 
 class StreamWriteObserver {
  public:
   // Sent when space becomes available in the stream, and the source should
   // resume writing.
   virtual void OnSpaceAvailable(Stream* stream) = 0;
 
+  // Sent when the stream is closed, and the writer should stop sending data.
+  virtual void OnClose(Stream* stream) = 0;
+
  protected:
   virtual ~StreamWriteObserver() {}
 };
 
 }  // namespace content
 
 #endif  // CONTENT_BROWSER_STREAMS_STREAM_WRITE_OBSERVER_H_