mount_operation, mounting the volume that contains the file this.
When this operation has completed,
callback will be called with
user_user data, and the operation can be finalized
cancellable is not null, then the operation can be cancelled by triggering the cancellable
object from another thread. If the operation was cancelled, the error g_io_error_cancelled will be returned.
flags affecting the operation
a MountOperation or null to avoid user interaction
optional Cancellable object, null to ignore
a TaskReadyCallback to call when the request is satisfied, or null
the data to pass to callback function