Function cef_uriencode 

pub unsafe extern "C" fn cef_uriencode(
    text: *const cef_string_t,
    use_plus: c_int,
) -> cef_string_userfree_t

Escapes characters in |text| which are unsuitable for use as a query parameter value. Everything except alphanumerics and -_.!~*’() will be converted to “%XX”. If |use_plus| is true (1) spaces will change to “+”. The result is basically the same as encodeURIComponent in Javacript.