A modified version of Thomas's comment:
Chromium-based browser: location.href.search(/[,\/]chromewebdata/i) != -1 && loadTimeData.data_.summary.failedUrl || location.href;
location.href.search(/[,\/]chromewebdata/i) != -1 && loadTimeData.data_.summary.failedUrl || location.href;
Firefox: location.href
location.href