AFAIK, it uses NPAPI plugin. Chrome stopped supporting NPAPI plugins, but that only means user can't install them, Google chooses now what plugins you should ha

AFAIK, it uses NPAPI plugin. Chrome stopped supporting NPAPI plugins, but that only means user can't install them, Google chooses now what plugins you should have, and it bundles Flash and Hangouts with browser. These plugins are well hidden, no more chrome://plugins and I can't find them in filesystem. You can see "Extension: Google Hangouts" in Chrome Task Manager when Hangouts is active. But I still think it's not malicious trick for browser wars, more likely that they abandoned Hangouts and will shut it down after some time, launching even more half-working chat services before that, with machine learning, VR, brands engagement, integrated video news and other crap everyone can't live without.