in components/tabs/src/storage.rs [743:753]
fn is_url_syncable(url: &str) -> bool {
url.len() <= URI_LENGTH_MAX
&& !(url.starts_with("about:")
|| url.starts_with("resource:")
|| url.starts_with("chrome:")
|| url.starts_with("wyciwyg:")
|| url.starts_with("blob:")
|| url.starts_with("file:")
|| url.starts_with("moz-extension:")
|| url.starts_with("data:"))
}