Dredging

To be entirely too precise about it, "dredging a chicken" means "sprinkling" some substance on it.

Almost invariably, the author is referring to flour or seasoned flour. And the author almost never actually expects you to "sprinkle" the flour on the chicken. More commonly what you would do is dip the chicken in flour you have put in a bowl or on a plate. Or you put the flour and chicken in a paper bag and shake.