An issue in Google Chrome preventing Lighthouse Experiments

[alekseykulikov]

Inspired by WPT experiments, I tried to implement them for Lighthouse using puppeteer's request interception. It almost worked but there's a bug in Google Chrome: requests interception API doesn't allow to return Gzip response. Here's the repo to reproduce it. This bug breaks Lighthouse metrics significantly (100kb body response vs. 500kb degrades LH score).

I shared the bug with @paulirish he hinted it could be easily fixed. I hope that this issue brings awareness to this minor problem preventing Lighthouse Experiments.

[connorjclark]

related: ChromeDevTools/rfcs#4 (in Lightrider/PSI, we've had to defer to response headers for the actual content size fetched on the network, so perhaps we could do the same for this use case). Could perhaps work today if you forced global.isLightrider = true and set X-TotalFetchedSize response header.