Patch 3 in the series.

WebCore/Modules/filesystem/DOMFileSystem.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 130 matching lines @@
     ASSERT(fileEntry);
 
     RefPtr<FileWriter> fileWriter = FileWriter::create(scriptExecutionContext());
     RefPtr<FileWriterBaseCallback> conversionCallback = ConvertToFileWriterCallback::create(successCallback);
     OwnPtr<FileWriterBaseCallbacks> callbacks = FileWriterBaseCallbacks::create(fileWriter, conversionCallback, errorCallback);
     m_asyncFileSystem->createWriter(fileWriter.get(), createFileSystemURL(fileEntry), callbacks.release());
 }
 
 namespace {
 
-class GetMetadataCallback : public FileSystemCallbacksBase {
+class SnapshotFileCallback : public FileSystemCallbacksBase {
 public:
-    static PassOwnPtr<GetMetadataCallback> create(PassRefPtr<DOMFileSystem> filesystem, const String& name, const KURL& url, PassRefPtr<FileCallback> successCallback, PassRefPtr<ErrorCallback> errorCallback)
+    static PassOwnPtr<SnapshotFileCallback> create(PassRefPtr<DOMFileSystem> filesystem, const String& name, const KURL& url, PassRefPtr<FileCallback> successCallback, PassRefPtr<ErrorCallback> errorCallback)
     {
-        return adoptPtr(new GetMetadataCallback(filesystem, name, url, successCallback, errorCallback));
+        return adoptPtr(new SnapshotFileCallback(filesystem, name, url, successCallback, errorCallback));
     }
 
-    virtual void didReadMetadata(const FileMetadata& metadata)
+    virtual void didCreateSnapshotFile(const FileMetadata& metadata, PassRefPtr<BlobDataHandle> snapshot)
     {
         ASSERT(!metadata.platformPath.isEmpty());
         if (!m_successCallback)
             return;
 
+        // 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).
         // FIXME: We should use the snapshot metadata for all files.
         // https://www.w3.org/Bugs/Public/show_bug.cgi?id=17746
         if (m_filesystem->type() == FileSystemTypeTemporary || m_filesystem->type() == FileSystemTypePersistent) {
             m_successCallback->handleEvent(File::createWithName(metadata.platformPath, m_name).get());
         } else if (!metadata.platformPath.isEmpty()) {
             // If the platformPath in the returned metadata is given, we create a File object for the path.
             m_successCallback->handleEvent(File::createForFileSystemFile(m_name, metadata).get());
         } else {
             // Otherwise create a File from the FileSystem URL.
             m_successCallback->handleEvent(File::createForFileSystemFile(m_url, metadata).get());
         }
 
         m_successCallback.release();
     }
 
 private:
-    GetMetadataCallback(PassRefPtr<DOMFileSystem> filesystem, const String& name,  const KURL& url, PassRefPtr<FileCallback> successCallback, PassRefPtr<ErrorCallback> errorCallback)
+    SnapshotFileCallback(PassRefPtr<DOMFileSystem> filesystem, const String& name,  const KURL& url, PassRefPtr<FileCallback> successCallback, PassRefPtr<ErrorCallback> errorCallback)
         : FileSystemCallbacksBase(errorCallback)
         , m_filesystem(filesystem)
         , m_name(name)
         , m_url(url)
         , m_successCallback(successCallback)
     {
     }
 
     RefPtr<DOMFileSystem> m_filesystem;
     String m_name;
     KURL m_url;
     RefPtr<FileCallback> m_successCallback;
 };
 
 } // namespace
 
 void DOMFileSystem::createFile(const FileEntry* fileEntry, PassRefPtr<FileCallback> successCallback, PassRefPtr<ErrorCallback> errorCallback)
 {
     KURL fileSystemURL = createFileSystemURL(fileEntry);
-    m_asyncFileSystem->createSnapshotFileAndReadMetadata(fileSystemURL, GetMetadataCallback::create(this, fileEntry->name(), fileSystemURL, successCallback, errorCallback));
+    m_asyncFileSystem->createSnapshotFileAndReadMetadata(fileSystemURL, SnapshotFileCallback::create(this, fileEntry->name(), fileSystemURL, successCallback, errorCallback));
 }
 
 } // namespace WebCore
 
 #endif // ENABLE(FILE_SYSTEM)