The Chrome Web Store has updated its policy concerning extensions with crypto-mining scripts, outright banning such extensions from the store. Any existing extensions that can be used for mining cryptocurrencies will be removed by the end of June 2018. While the policy will prevent future extensions that are obviously used for crypto-mining, it remains to be seen if this will solve the problem of surreptitious mining scripts hidden in otherwise innocuous extensions.
https://www.notebookcheck.net/Chrome-Web-Store-bans-extensions-that-mine-cryptocurrencies.294852.0.html