Page callback: Presents the custom block edit form.
Drupal\custom_block\Plugin\Core\Entity\CustomBlock $block: The custom block to edit.
array A form array as expected by drupal_render().
function custom_block_edit(CustomBlock $block) {
drupal_set_title(t('Edit custom block %label', array(
'%label' => $block
->label(),
)), PASS_THROUGH);
return entity_get_form($block);
}