Implements \Drupal\Core\Form\FormInterface::submitForm().
Overrides SystemConfigFormBase::submitForm
public function submitForm(array &$form, array &$form_state) {
drupal_clear_css_cache();
drupal_clear_js_cache();
// This form allows page compression settings to be changed, which can
// invalidate the page cache, so it needs to be cleared on form submit.
$this->pageCache
->deleteAll();
$this->configFactory
->get('system.performance')
->set('cache.page.use_internal', $form_state['values']['cache'])
->set('cache.page.max_age', $form_state['values']['page_cache_maximum_age'])
->set('response.gzip', $form_state['values']['page_compression'])
->set('css.preprocess', $form_state['values']['preprocess_css'])
->set('js.preprocess', $form_state['values']['preprocess_js'])
->save();
parent::submitForm($form, $form_state);
}