Google, Mozilla and Opera - "WebRTC":
http://caniuse.com/#search=WebRTC and http://en.wikipedia.org/wiki/WebRTC
Microsoft proposed another draft "CU-RTC-WEB" based on Skype details: http://en.wikipedia.org/wiki/CU-RTC-WEB and later "ORTC": http://www.infoq.com/news/2014/08/ortc-webrtc
Hangout vs. Skype vs. iOS messages is the deal breaker why WebRTC isn't suppored in Safari and IE. That's sad as it already works in ~1.7B devices.