wp-admin/includes/class-wp-upgrader-skin.php:147Displays the header before the update process.
public function header() { if ( $this->done_header ) { return; } $this->done_header = true; echo '<div class="wrap">'; echo '<h1>' . $this->options['title'] . '</h1>'; }Introduced in 2.8.0. Unchanged from 6.7.7 through 7.1.0.
Signature, return type and hooks compared across 5 parsed releases.
src/wp-admin/includes/class-wp-upgrader-skin.php, and regenerated for each WordPress release so it tracks the code rather than a snapshot of it.