This is entirely about Google trying to deal with ad click fraud. They desperately want a solution in the browser. They will ship this, standard or not. But

This is entirely about Google trying to deal with ad click fraud. They desperately want a solution in the browser. They will ship this, standard or not. But I don't see a reason for Apple to ship this in Safari, or Firefox neither. So I expect this will be a real test of Chrome's market power. Will any sites start blocking non-WEI browsers? Locking out iPhones seems insane. Or will we see differential ad rates for WEI environments?