Patch 3 in the series.

WebCore/Modules/filesystem/DOMFileSystemSync.cpp

 /*
  * 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 95 matching lines @@
     virtual void didFail(int code)
     {
         m_result->m_failed = true;
         m_result->m_code = code;
     }
 
     virtual ~CreateFileHelper()
     {
     }
 
-    void didReadMetadata(const FileMetadata& metadata)
+    virtual void didCreateSnapshotFile(const FileMetadata& metadata, PassRefPtr<BlobDataHandle> snapshot)
     {
+        // We can't directly use the snapshot blob data handle because the content type on it hasn't been set.
+        // The |snapshot| param is here to provide a a chain of custody thru thread bridging that is held onto until
+        // *after* we've coined a File with a new handle that has the correct type set on it. This allows the
+        // blob storage system to track when a temp file can and can't be safely deleted.
+
         // For regular filesystem types (temporary or persistent), we should not cache file metadata as it could change File semantics.
-        // For other filesystem types (which could be platform-specific ones), there's a chance that the files are on remote filesystem. If the port has returned metadata just pass it to File constructor (so we may cache the metadata).
+        // For other filesystem types (which could be platform-specific ones), there's a chance that the files are on remote filesystem.
+        // If the port has returned metadata just pass it to File constructor (so we may cache the metadata).
         // FIXME: We should use the snapshot metadata for all files.
         // https://www.w3.org/Bugs/Public/show_bug.cgi?id=17746
         if (m_type == FileSystemTypeTemporary || m_type == FileSystemTypePersistent) {
             m_result->m_file = File::createWithName(metadata.platformPath, m_name);
         } else if (!metadata.platformPath.isEmpty()) {
             // If the platformPath in the returned metadata is given, we create a File object for the path.
             m_result->m_file = File::createForFileSystemFile(m_name, metadata).get();
         } else {
             // Otherwise create a File from the FileSystem URL.
             m_result->m_file = File::createForFileSystemFile(m_url, metadata).get();
@@ skipping 121 matching lines @@
         return 0;
     }
     ASSERT(successCallback->fileWriterBase());
     ASSERT(static_cast<FileWriterSync*>(successCallback->fileWriterBase()) == fileWriter.get());
     return fileWriter;
 }
 
 }
 
 #endif // ENABLE(FILE_SYSTEM)