7 string references to 'system.theme'

system_update_8041 in drupal/core/modules/system/system.install
Convert admin_theme variable to config.
ThemeController::create in drupal/core/modules/system/lib/Drupal/system/Controller/ThemeController.php
Instantiates a new instance of this controller.
theme_disable in drupal/core/includes/theme.inc
Disables a given list of themes.
theme_enable in drupal/core/includes/theme.inc
Enables a given list of themes.
UpdateContribTest::testUpdateShowDisabledThemes in drupal/core/modules/update/lib/Drupal/update/Tests/UpdateContribTest.php
Tests that disabled themes are only shown when desired.
update_prepare_d8_bootstrap in drupal/core/includes/update.inc
Performs extra steps required to bootstrap when using a Drupal 7 database.
_drupal_maintenance_theme in drupal/core/includes/theme.maintenance.inc
Sets up the theming system for maintenance page.