There is a Firefox addon in the profile directory agents/templates/Firefox.
Where is the logic for calculating Time to first byte, content Download, Server IP etc for embedded content.
I see that nsIWebProgressListener has been used but I am not able to find the code for calculating above.
The timings are not recorded from the extension. The extensions are only used to drive the browser navigation, interact with the DOM and get notifications when the page load is complete.
The core of webpagetest’s logic is in wpthook.dll which is injected into the browser process and intercepts the networking API calls.