That GitHub discussion seems to confirm it. The developers shutting down their extension immediately afterwards too just reeks of suspicious activity.

The version number for the extension in my browser (1.8.8) doesn’t match the latest release that’s visible on this otherwise public repository (1.8.0)

So presumably at some point “someone” “somewhere” modified or added some files to the source code of this extension out of public view… and then “somehow” got a hold of this dev account password or whatever which was subsequently used to surreptitiously push it to the chrome webstore…