>abusing their market position in a manner that's harmful to the public.
Why is it abuse? No one is being forced to use chromium. Are you abusing your market position when you buy the cheapest toothbrush in a manner that's harmful to other toothbrush companies?
However, due to marketshare, the other browsers do tend to be forced to implement the same features as Chromium/Chrome.
Google can easily force the other browsers to lose the Web Request API, because maintaining it when they're the only ones using it is a net loss of productivity, which will probably be needed elsewhere.
Why is it abuse? No one is being forced to use chromium. Are you abusing your market position when you buy the cheapest toothbrush in a manner that's harmful to other toothbrush companies?