This demo shows the auto height feature of wrapped iframes which is supported since 7.0. So if you have an iframe which contains another iframe also the height of the outer iframe is recalculated. This works on the same domain and when you can use the external workaround.
For this demo the "Show Content Only" plugin with "Content + Styles" mode is used to show only the content and the <head> section inside the iframe. "Content only" does not work as the needed Javascript would not be rendered. If you render ai.js to the footer you need to set include_scripts_in_content="true" in the inner iframe that the needed Javascript is available.
Click on the link in the inner iframe which switches between 2 pages with different heights. Also the height of the outer iframe is changes than. You don't have to configure anything extra next to the auto height feature!
This is the shortcode of the green iframe:
[advanced_iframe securitykey="da39a3ee5e6b4b0d3255bfef95601890afd80709" use_shortcode_attributes_only="true" src="//www.tinywebgallery.com/blog/advanced-iframe/demo-advanced-iframe-2-0/same-domain-wrapped-auto-height/same-domain-wrapped-iframe-1?content-only=1&css=1" height="200" width="100%" onload_resize="true" style="outline:1px solid green" scrolling="no" iframe_content_id="body" iframe_content_styles="padding:10px;"]