Implements hook_views_form_substitutions().
function action_views_form_substitutions() {
// Views check_plain()s the column label, so we need to match that.
$select_all_placeholder = check_plain('<!--action-bulk-form-select-all-->');
$select_all = array(
'#type' => 'checkbox',
'#default_value' => FALSE,
'#attributes' => array(
'class' => array(
'action-table-select-all',
),
),
);
return array(
$select_all_placeholder => drupal_render($select_all),
);
}