function groupByDomain(groupSubdomains, node)
        {
            var url = WebInspector.TimelineTreeView.eventURL(node.event) || "";
            if (url.startsWith("extensions::"))
                return WebInspector.UIString("[Chrome extensions overhead]");
            var parsedURL = url.asParsedURL();
            if (!parsedURL)
                return "";
            if (parsedURL.scheme === "chrome-extension") {
                url = parsedURL.scheme + "://" + parsedURL.host;
                var displayName = executionContextNamesByOrigin.get(url);
                return displayName ? WebInspector.UIString("[Chrome extension] %s", displayName) : url;
            }
            if (!groupSubdomains)
                return parsedURL.host;
            if (/^[.0-9]+$/.test(parsedURL.host))
                return parsedURL.host;
            var domainMatch = /([^.]*\.)?[^.]*$/.exec(parsedURL.host);
            return domainMatch && domainMatch[0] || "";
        }
@param {boolean} groupSubdomains
@param {!WebInspector.TimelineModel.ProfileTreeNode} node
@return {string}