Redirect host browser to product page from embedded iframe

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I use Extension app and have extra button at product page.
On click this button it opens app page within iframe in a browser. src url of iframe have id of the product and i can do the thing there.
After user have finished within iframe I want to get his browser back to product page. 
I do not use app-bridge so I cannot use 'Redirect' action. 

What message can I post to the host page so it would redirect user's browser to product page?

if there is no message, then what is the correct way to achieve the goal?