Function cef_string_utf16_to_lower 

pub unsafe extern "C" fn cef_string_utf16_to_lower(
    src: *const char16_t,
    src_len: usize,
    output: *mut cef_string_utf16_t,
) -> c_int

These functions convert utf16 string case using the current ICU locale. This may change the length of the string in some cases.