RockMelt has unveiled the public beta of its new Web browser featuring built-in social network sharing. Named after the company, the browser is built on Google Chromium. Its integration with Facebook is so tight that users must log into that social networking site first in order to use the browser. The RockMelt browser keeps track of a user’s favorite sites. However, the concept of integrating a browser with social networking features isn’t exactly new — Flock, an alternative browser that’s been in the market for some time and is also based on Chromium.