Gmail Auto Clean Up (http://se-suganuma.blogspot.jp/2013/10/google-apps-scriptgmail.html)

main.js

function cleanUp() {
	//
	// Settings
	//
	// Enter # of days before messages are moved to trash
	var days = 7;

	// List of labels which you want to remove
	var filters = [];
	filters.push('label:notification-mailmagazine');
	filters.push('label:notification-facebook');
	filters.push('label:notification-google+');
	filters.push('label:notification-schedule');
	filters.push('label:notification-twitter');

	// If it found many threads,
	// the loop method will be stop at around 250.
	var max = 200;


	//
	// Generate Search Query
	//
	var query = [];
	query.push('(');
	query.push(filters.join(' OR '));
	query.push(')');
	query.push('is:read');
	query.push('older_than:' + days + 'd');
	query = query.join(' ');

	// Excute
	//Logger.log(query); // for Debug
	var threads = GmailApp.search(query);
	if (!threads) {return false;}
	for (var i = 0; i < max; i++) {
		if (threads[i]) {
			threads[i].moveToTrash();

			// for Debug
			//messages = threads[i].getMessages();
			//for (var j = 0; j < messages.length; j++) {
			//	Logger.log(messages[j].getSubject());
			//}
		}
	}
}