Source

File: wp-includes/class-wp-customize-setting.php

final public function check_capabilities() {
		if ( $this->capability && ! current_user_can( $this->capability ) ) {
			return false;
		}

		if ( $this->theme_supports && ! current_theme_supports( ... (array) $this->theme_supports ) ) {
			return false;
		}

		return true;
	}