code: function getPageScaleFactor() {
      const pageScaleFactor = chrome.gpuBenchmarking.pageScaleFactor;
      return pageScaleFactor ? pageScaleFactor.apply(chrome.gpuBenchmarking) : 1;
    }
docs: Chrome version before M50 doesn't have `pageScaleFactor` function, to run benchmark on them we will need this function to fail back gracefully