From the comment in https://codereview.chromium.org/2684143002/diff/80001/content/browser/web_contents/web_contents_impl.cc#newcode3312

Dominic mentioned that this area doesn't have test coverage. I've kept the old behavior of calling the BAM method on the old RFHI, but it would be good to have tests for this to show that the call has to be done on it and not the new one (and does it actually matter in practice?)