Implements hook_field_storage_delete().
function field_test_field_storage_delete($entity_type, $entity, $fields) {
list($id, $vid, $bundle) = entity_extract_ids($entity_type, $entity);
// Note: reusing field_test_storage_purge(), like field_sql_storage.module
// does, is highly inefficient in our case...
foreach (field_info_instances($bundle) as $instance) {
if (isset($fields[$instance['field_id']])) {
$field = field_info_field_by_id($instance['field_id']);
field_test_field_storage_purge($entity_type, $entity, $field, $instance);
}
}
}