This interface provides a means for enumerating the contents of a directory.
It is similar to nsISimpleEnumerator except the retrieved entries are QI’ed
to nsIFile, and there is a mechanism for closing the directory when the
enumeration is complete.
Closes the directory being enumerated, releasing the system resource.
@throws NS_OK if the call succeeded and the directory was closed.
NS_ERROR_FAILURE if the directory close failed.
It is safe to call this function many times.
Retrieves the next file in the sequence. The “nextFile” element is the
first element upon the first call. This attribute is null if there is no
next element.