Javascript,删除历史记录中的最后一项(firefox addon)

// 获取浏览器历史记录服务
var {Cc, Ci} = require("chrome");
var historyService = Cc["@mozilla.org/browser/nav-history-service;1"].getService(Ci.nsINavHistoryService);

// 获取最后一项历史记录
var query = historyService.getNewQuery();
var options = historyService.getNewQueryOptions();
options.sortingMode = options.SORT_BY_DATE_DESCENDING;
options.resultType = options.RESULTS_AS_URI;
query.setFolders([historyService.getPlacesRoot()], 1);
var result = historyService.executeQuery(query, options);
var rootNode = result.root;
rootNode.containerOpen = true;
var lastItemIndex = rootNode.childCount - 1;
var lastItem = rootNode.getChild(lastItemIndex);

// 删除最后一项历史记录
historyService.removePage(lastItem.itemId);

// 关闭历史记录服务
rootNode.containerOpen = false;