Asynchronously gets the requested information about the filesystem that the specified this is on.
The result is a FileInfo object that contains key-value attributes (such as type or size for the file).
For more details, see query_filesystem_info which is the synchronous version of this call.
When the operation is finished,
callback will be called. You can then call
query_info_async.end to get the result of the operation.
an attribute query string
the I/O priority of the request
optional Cancellable object, null to ignore
a TaskReadyCallback to call when the request is satisfied
the data to pass to callback function