I would like to add a top bar to wordpress without having to edit any theme files. Are there any filters that I can use to achieve this.

I want to be able to do this in the function.php file. This way it is easy to just dump in the code in the future without having to worry about changing the code in the theme files.

If there are no filters that can do this then I will use the header.php file in a child theme to do make the changes.