Does DRM work on iOS in Chrome/Firefox browsers?

The only mobile browser on iOS, which is able to play Fairplay DRM protected content, is Safari, or a native application that is using the Fairplay SDK.

According to Apple App Store review guidelines, every browser has to be built using Webkit framework and Webkit Javascript implementation, which is also used by Safari. So other iOS Browsers like Chrome or Firefox can only leverage what is supported by the Webkit Framework, which excludes Fairplay DRM support at the moment.