In extensions (and planned for BigTree 4.3), field types gain a more consolidated directory structure. Each field type stores all of its files in a single directory rather than spreading across 3 directories. When including a field type in an extension, this new directory/file structure will occur automatically.
New paths for each of the old files are:
/custom/admin/form-field-types/draw/{id}.php/extensions/field-types/{id}/draw.php/custom/admin/form-field-types/process/{id}.php
/extensions/field-types/{id}/process.php/custom/admin/ajax/developer/field-options/{id}.php/extensions/field-types/{id}/options.php