Macro wrap_delete_cookies_callback 

macro_rules! wrap_delete_cookies_callback {
    ($ vis : vis struct $ name : ident ; impl DeleteCookiesCallback { $ ($ (# [$ attrs_name : meta]) * fn $ method_name : ident (& $ self : ident $ (, $ arg_name : ident : $ arg_type : ty) * $ (,) ?) $ (-> $ return_type : ty) ? { $ ($ body : tt) * }) * }) => { ... };
    ($ vis : vis struct $ name : ident $ (< $ ($ generic_type : ident : $ first_generic_type_bound : tt $ (+ $ generic_type_bound : tt) *) , + $ (,) ? >) ? { $ ($ field_vis : vis $ field_name : ident : $ field_type : ty) , * $ (,) ? } impl DeleteCookiesCallback { $ ($ (# [$ attrs_name : meta]) * fn $ method_name : ident (& $ self : ident $ (, $ arg_name : ident : $ arg_type : ty) * $ (,) ?) $ (-> $ return_type : ty) ? { $ ($ body : tt) * }) * }) => { ... };
}

Implement the WrapDeleteCookiesCallback trait for the specified struct. You can declare more members for your struct, and in the impl DeleteCookiesCallback block you can override default methods implemented by the ImplDeleteCookiesCallback trait.

Example

wrap_delete_cookies_callback! {
    struct MyDeleteCookiesCallback {
        payload: String,
    }

    impl DeleteCookiesCallback {
        // ...
    }
}

fn make_my_struct() -> DeleteCookiesCallback {
    MyDeleteCookiesCallback::new("payload".to_string())
}