That makes no sense whatsoever. There are a few websites which do request it, and the header will do no harm to the ones that don't. So Chrome users will be una

That makes no sense whatsoever. There are a few websites which do request it, and the header will do no harm to the ones that don't. So Chrome users will be unable to use that feature (going to be?) supported by Twitter, for example. Did Google web properties use WebGL, NaCl etc. before Chrome supported them?