The title is incorrect - it should remove the "OS" part. ARC means "App Runtime for Chrome", it is not specific to Chrome OS.
That isn't a trivial difference - it matters. This is Google bringing Android apps to Chrome - on Mac, on Windows, on Linux, on Chrome OS - and not just to Chrome OS. In other words, Chrome isn't just a browser, it also does things that have nothing to do with being a browser.
That isn't a trivial difference - it matters. This is Google bringing Android apps to Chrome - on Mac, on Windows, on Linux, on Chrome OS - and not just to Chrome OS. In other words, Chrome isn't just a browser, it also does things that have nothing to do with being a browser.