Implement Blob.close().

Source/core/dom/DOMURL.cpp

 /*
  * Copyright (C) 2011 Google Inc. All rights reserved.
  * Copyright (C) 2012 Motorola Mobility Inc.
  *
  * Redistribution and use in source and binary forms, with or without
  * modification, are permitted provided that the following conditions
  * are met:
  *
  * 1.  Redistributions of source code must retain the above copyright
  *     notice, this list of conditions and the following disclaimer.
@@ skipping 49 matching lines @@
     } else {
         m_url = KURL();
         m_input = value;
     }
 }
 
 String DOMURL::createObjectURL(ExecutionContext* executionContext, Blob* blob)
 {
     if (!executionContext || !blob)
         return String();
-    return createPublicURL(executionContext, blob);
+    return createPublicURL(executionContext, blob, blob->uuid());
 }
 
-String DOMURL::createPublicURL(ExecutionContext* executionContext, URLRegistrable* registrable)
+String DOMURL::createPublicURL(ExecutionContext* executionContext, URLRegistrable* registrable, const String& uuid)

[michaeln, 2014/02/12 20:33:04]

Not sure we need the addition of the uuid? The balancing call to revoke all for
a registrable object could use the URLRegistrable* value as the key. Not all
registerable object types have seperate string uuids associated with them, if
the ptr value can serve as the key, they too can be revoked.

Any reason to not use the ptr value as the key? I guess internal data structs
should view the key as a void* since URLRegistrations can outlive the Blob
object.

API'wise, it might be nice to provide a balancing method to revoke all for a
registerable defined on this DOMURL class since this is where they're created.

[sof, 2014/02/12 22:28:26]

I like the idea of using the URLRegistrable* as the unique value, will have to
think about it overnight.

There are some issues though -- when the Blobs become objects on the Oilpan
heap, you suddenly have to contend with references to GCed objects. And you have
to retire/disable a URLRegistrable* once it becomes garbage..as you don't want
to run the risk of having false matches when you do close() a Blob & pass along
its pointer value. i.e., the same pointer value could have belonged to an
earlier Blob...and you're not allowed to revoke URLs upon their associated Blob
being garbage collected.

[michaeln, 2014/02/12 22:34:11]

Right, that's sounds like a very good reason to not use the ptr value as the
key.

 {
     KURL publicURL = BlobURL::createPublicURL(executionContext->securityOrigin());
     if (publicURL.isEmpty())
         return String();
 
-    executionContext->publicURLManager().registerURL(executionContext->securityOrigin(), publicURL, registrable);
+    executionContext->publicURLManager().registerURL(executionContext->securityOrigin(), publicURL, registrable, uuid);
 
     return publicURL.string();
 }
 
 void DOMURL::revokeObjectURL(ExecutionContext* executionContext, const String& urlString)
 {
     if (!executionContext)
         return;
 
     KURL url(KURL(), urlString);
     MemoryCache::removeURLFromCache(executionContext, url);
     executionContext->publicURLManager().revoke(url);
 }
 
 } // namespace WebCore