Function cef_register_scheme_handler_factory 

pub unsafe extern "C" fn cef_register_scheme_handler_factory(
    scheme_name: *const cef_string_t,
    domain_name: *const cef_string_t,
    factory: *mut cef_scheme_handler_factory_t,
) -> c_int

Register a scheme handler factory with the global request context. An NULL |domain_name| value for a standard scheme will cause the factory to match all domain names. The |domain_name| value will be ignored for non-standard schemes. If |scheme_name| is a built-in scheme and no handler is returned by |factory| then the built-in scheme handler factory will be called. If |scheme_name| is a custom scheme then you must also implement the cef_app_t::on_register_custom_schemes() function in all processes. This function may be called multiple times to change or remove the factory that matches the specified |scheme_name| and optional |domain_name|. Returns false (0) if an error occurs. This function may be called on any thread in the browser process. Using this function is equivalent to calling cef_reques t_context_t::cef_request_context_get_global_context()->register_scheme_handl er_factory().