Hinaloe

<blockquote>
You no longer have to use this plugin because it was merged to <a href="https://ja.wordpress.org/plugins/public-post-preview/" rel="nofollow ugc">PPP plugin</a> at v2.6.0.
</blockquote>
This plugin send <code>Cache-Control: no-cache, must-revalidate</code> header when show <a href="https://wordpress.org/plugins/public-post-preview/" rel="ugc">public-post-preview</a> post.
In other word, that make skip cache of CDN (like CloudFlare, CloudFront… and other), or Proxy-Cache (Like Nginx). 
So, outside people always can see newest draft, and there is no need extra time to close public draft.
This plugin needs PHP 5.3+
Note: If you’re using CloudFront, you should also use <a href="https://wordpress.org/plugins/c3-cloudfront-clear-cache/" rel="ugc">C3 Cloudfront Cache Controller</a>

Non Cache Public Post Preview

Disable cache when show public post preview post

marobins

This plugin will allow you to embed a chat from Public right into your WordPress blog.

PBLC Embed Chat Creator

This plugin will allow you to embed a chat from Public right into your WordPress blog.

Non Cache Public Post Preview vs PBLC Embed Chat Creator