Chrome in Metro also includes Flash, courtesy of Google's long-bundling of the Adobe software with the browser. That puts Chrome in the same category as , which in Metro can also render Flash.

Even though Metro is supposed to be plug-in free, both Google and Microsoft have circumvented the rule by integrating Flash Player with their browsers.

Mozilla, which is working on a Metro-ized version of Firefox for Windows 8, and has , had mixed thoughts on the trend.

"We think there should be equal access to platform capabilities and while we encourage healthy competition, believe there should be no circumstances that give any browser an unfair advantage," said Asa Dotzler, director of Firefox, in an email reply to questions about IE10's use of Flash last week. "[But] if other browsers can bring Flash or plug-ins in general to Metro, then it doesn't seem to be a problem. But that isn't clear at this time."

Dotzler comment was made before Google rolled out the Metro preview of Chrome with Flash included.