wp_update_https_migration_required( mixed $old_url, mixed $new_url )

Source

File: wp-includes/https-migration.php

function wp_update_https_migration_required( $old_url, $new_url ) {
	// Do nothing if WordPress is being installed.
	if ( wp_installing() ) {
		return;
	}

	// Delete/reset the option if the new URL is not the HTTPS version of the old URL.
	if ( untrailingslashit( (string) $old_url ) !== str_replace( 'https://', 'http://', untrailingslashit( (string) $new_url ) ) ) {
		delete_option( 'https_migration_required' );
		return;
	}

	// If this is a fresh site, there is no content to migrate, so do not require migration.
	$https_migration_required = get_option( 'fresh_site' ) ? false : true;

	update_option( 'https_migration_required', $https_migration_required );
}