:OnLoadingStateChange will be called twice in all cases. If the navigation is allowed cef_load_handler_t::OnLoadStart and
:OnLoadEnd will be called. If the navigation is canceled cef_load_handler_t::OnLoadError will be called with an |errorCode| value of ERR_ABORTED. The |user_gesture| value will be true (1) if the browser navigated via explicit user gesture (e.g. clicking a link) or false (0) if it navigated automatically (e.g. via the DomContentLoaded event).
Called on the UI thread before browser navigation. Return true (1) to cancel the navigation or false (0) to allow the navigation to proceed. The |request| object cannot be modified in this callback.