Reland r187230: Implement the Stream registry in content

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;
+
+ protected:
+  virtual ~StreamWriteObserver() {}
+};
+
+}  // namespace content
+
+#endif  // CONTENT_BROWSER_STREAMS_STREAM_WRITE_OBSERVER_H_