Theme_Upgrader::bulk_upgrade( array $themes, array $args = array() )

	public function bulk_upgrade( $themes, $args = array() ) {

		$defaults = array(
			'clear_update_cache' => true,
		);
		$parsed_args = wp_parse_args( $args, $defaults );

		$this->init();
		$this->bulk = true;
		$this->upgrade_strings();

		$current = get_site_transient( 'update_themes' );

		add_filter('upgrader_pre_install', array($this, 'current_before'), 10, 2);
		add_filter('upgrader_post_install', array($this, 'current_after'), 10, 2);
		add_filter('upgrader_clear_destination', array($this, 'delete_old_theme'), 10, 4);

		$this->skin->header();

		// Connect to the Filesystem first.
		$res = $this->fs_connect( array(WP_CONTENT_DIR) );
		if ( ! $res ) {
			$this->skin->footer();
			return false;
		}

		$this->skin->bulk_header();

		// Only start maintenance mode if:
		// - running Multisite and there are one or more themes specified, OR
		// - a theme with an update available is currently in use.
		// @TODO: For multisite, maintenance mode should only kick in for individual sites if at all possible.
		$maintenance = ( is_multisite() && ! empty( $themes ) );
		foreach ( $themes as $theme )
			$maintenance = $maintenance || $theme == get_stylesheet() || $theme == get_template();
		if ( $maintenance )
			$this->maintenance_mode(true);

		$results = array();

		$this->update_count = count($themes);
		$this->update_current = 0;
		foreach ( $themes as $theme ) {
			$this->update_current++;

			$this->skin->theme_info = $this->theme_info($theme);

			if ( !isset( $current->response[ $theme ] ) ) {
				$this->skin->set_result(true);
				$this->skin->before();
				$this->skin->feedback( 'up_to_date' );
				$this->skin->after();
				$results[$theme] = true;
				continue;
			}

			// Get the URL to the zip file
			$r = $current->response[ $theme ];

			$result = $this->run( array(
				'package' => $r['package'],
				'destination' => get_theme_root( $theme ),
				'clear_destination' => true,
				'clear_working' => true,
				'is_multi' => true,
				'hook_extra' => array(
					'theme' => $theme
				),
			) );

			$results[$theme] = $this->result;

			// Prevent credentials auth screen from displaying multiple times
			if ( false === $result )
				break;
		} //end foreach $plugins

		$this->maintenance_mode(false);

		// Refresh the Theme Update information
		wp_clean_themes_cache( $parsed_args['clear_update_cache'] );

		/** This action is documented in wp-admin/includes/class-wp-upgrader.php */
		do_action( 'upgrader_process_complete', $this, array(
			'action' => 'update',
			'type' => 'theme',
			'bulk' => true,
			'themes' => $themes,
		) );

		$this->skin->bulk_footer();

		$this->skin->footer();

		// Cleanup our hooks, in case something else does a upgrade on this connection.
		remove_filter('upgrader_pre_install', array($this, 'current_before'));
		remove_filter('upgrader_post_install', array($this, 'current_after'));
		remove_filter('upgrader_clear_destination', array($this, 'delete_old_theme'));

		return $results;
	}