Ran across this about 3 months ago by pressing Ctrl + Shift + J instead of Ctrl + Shift + N for going incognito.
Pretty slick facility to analyze webpages. In the past I have reviewed similar applications, but this one is already built into the browser. I dont know, but would assume it would be available for other operating systems.
As always I would suggest you play with this to get the hang of all the various tabs and options before using it in the wild.