It is native Mac software, not a wrapper around a Chromium instance, and it behaves like a proper Mac app, too.
There's a contingent of the online Apple thinkers always hawking the "Made for Mac" applications and placing them up on the dais, but my experience is always the same:
The backwards-compatibility built into the browser is its' super power. The attitude that a Mac app is somehow the best version of a UI is a misattributed reaction to a bad website, which is unfortunately common place today because web developers have lost sight of the web's grain.
