Don't keep file system directories around if they contain unrelated files.

webkit/fileapi/obfuscated_file_util.h

 // Copyright (c) 2012 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #ifndef WEBKIT_FILEAPI_OBFUSCATED_FILE_UTIL_H_
 #define WEBKIT_FILEAPI_OBFUSCATED_FILE_UTIL_H_
 
 #include <map>
 #include <string>
 #include <vector>
@@ skipping 121 matching lines @@
       FileSystemOperationContext* context,
       const FileSystemURL& url) OVERRIDE;
 
   virtual base::PlatformFileError DeleteSingleDirectory(
       FileSystemOperationContext* context,
       const FileSystemURL& url) OVERRIDE;
 
   // Gets the topmost directory specific to this origin and type.  This will
   // contain both the directory database's files and all the backing file
   // subdirectories.
+  // Returns an empty path if the directory is undefined (e.g. because |type|
+  // is invalid). If the directory is defined, it will be returned, even if
+  // there is a file system error (e.g. the directory doesn't exist on disk and
+  // |create| is false). Callers should always check |error_code| to make sure
+  // the returned path is usable.
   FilePath GetDirectoryForOriginAndType(
       const GURL& origin,
       FileSystemType type,
       bool create,
       base::PlatformFileError* error_code);
 
-  FilePath GetDirectoryForOriginAndType(
-      const GURL& origin,
-      FileSystemType type,
-      bool create) {
-    return GetDirectoryForOriginAndType(origin, type, create, NULL);
-  }
-
   // Deletes the topmost directory specific to this origin and type.  This will
   // delete its directory database.
   bool DeleteDirectoryForOriginAndType(const GURL& origin, FileSystemType type);
 
   // This will migrate a filesystem from the old passthrough sandbox into the
   // new obfuscated one.  It won't obfuscate the old filenames [it will maintain
   // the old structure, but move it to a new root], but any new files created
   // will go into the new standard locations.  This will be completely
   // transparent to the user.  This migration is atomic in that it won't alter
   // the source data until it's done, and that will be with a single directory
@@ skipping 101 matching lines @@
   scoped_ptr<FileSystemOriginDatabase> origin_database_;
   FilePath file_system_directory_;
   base::OneShotTimer<ObfuscatedFileUtil> timer_;
 
   DISALLOW_COPY_AND_ASSIGN(ObfuscatedFileUtil);
 };
 
 }  // namespace fileapi
 
 #endif  // WEBKIT_FILEAPI_OBFUSCATED_FILE_UTIL_H_