PreloadController will be a WebStateDelegate for prerender WebStates, so there will be no need for WebState::ShouldSuppressDialogs and WebStateObserver::DidSuppressDialog API.
Instead PreloadController::GetJavaScriptDialogPresenter, PreloadController::OnAuthRequired and PreloadController::CreateNewWebState will cancel the prerender and block dialogs.
Comment 1 by eugene...@chromium.org
, Oct 24 2017