Currently, sandbox extensions for registered file blobs are tracked in WebKit2 in NetworkBlobRegistry, while the files itself are tracked in BlobRegistryImpl. This creates a potential for these getting out of sync. Also, I'm going to make WebCore read the files in some cases, so we'll need a way to consume extensions from WebCore code.
Created attachment 231077 [details] proposed patch
Committed <http://trac.webkit.org/r168478>.