Files: wp-admin/includes/class-theme-upgrader.php

Get the WP_Theme object for a theme.

Initialize the installation strings.

Check if a child theme is being installed and we need to install its parent.

Don’t display the activate and preview actions to the user.

Install a theme package.

Upgrade a theme.

Upgrade several themes at once.

Check that the package source contains a valid theme.

Turn on maintenance mode before attempting to upgrade the current theme.

Turn off maintenance mode after upgrading the current theme.

Delete the old theme during an upgrade.

Initialize the upgrade strings.

Upgrade a theme.

Upgrade several themes at once.

Check that the package source contains a valid theme.