Add method to abort Stream construction to BlobRegistry

public/platform/WebBlobRegistry.h

 /*
  * Copyright (C) 2010 Google Inc. All rights reserved.
  *
  * Redistribution and use in source and binary forms, with or without
  * modification, are permitted provided that the following conditions are
  * met:
  *
  *     * Redistributions of source code must retain the above copyright
  * notice, this list of conditions and the following disclaimer.
  *     * Redistributions in binary form must reproduce the above
@@ skipping 49 matching lines @@
     // type.
     virtual void registerStreamURL(const WebURL&, const WebString&) { WEBKIT_ASSERT_NOT_REACHED(); }
 
     // Registers a stream URL referring to the stream identified by the
     // specified srcURL.
     virtual void registerStreamURL(const WebURL&, const WebURL& srcURL) { WEBKIT_ASSERT_NOT_REACHED(); };
 
     // Add data to the stream referred by the URL.
     virtual void addDataToStream(const WebURL&, WebThreadSafeData&) { WEBKIT_ASSERT_NOT_REACHED(); }
 
-    // Tell the registry that this stream won't receive any more data.
+    // Tell the registry that construction of this stream has completed
+    // successfully and so it won't receive any more data.
     virtual void finalizeStream(const WebURL&) { WEBKIT_ASSERT_NOT_REACHED(); }
 
+    // Tell the registry that construction of this stream has been aborted and
+    // so it won't receive any more data.
+    virtual void abortStream(const WebURL&) { WEBKIT_ASSERT_NOT_REACHED(); }
+
     // Unregisters a stream referred by the URL.
     virtual void unregisterStreamURL(const WebURL&) { WEBKIT_ASSERT_NOT_REACHED(); }
 };
 
 } // namespace WebKit
 
 #endif // WebBlobRegistry_h