[folkrav]

Malware has a definition[1] :

> Malicious computer software that interferes with normal computer functions or sends personal data about the user to unauthorized parties over the Internet.

Taking up a couple KBs of space to do nothing is not even comparable. From a moral standpoint, was it okay from them to install that extension on people's computers? No. Was it malware? No.

[1] https://duckduckgo.com/?q=define+malware&t=h_&ia=definition