johncastlegate on "How to remove "Add Media" button in WP 3.5?"

In previous versions of WordPress, I could remove the media upload button with something like:

function z_remove_media_controls($context) {
    return;
}

add_action('media_buttons_context', 'z_remove_media_controls');

However, this does not seem to work in WordPress 3.5. How can I remove or hide the button now?