Add custom link to the contextual links of block in Drupal 7.
<?php
function ccl_block_contextual_links_view_alter(&$element, &$items) {
if (isset($element['#element']['#block']) && $element['#element']['#block']->delta == "custom_module") {
$element['#links']['edit_f_block'] = array(
'title' => 'Change Content',
'href' => url('admin/config/front/block', array('absolute' => TRUE)),
);
}
}
?>