UserAgent: Mozilla/5.0 (Windows NT 10.0; Win64; x64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/53.0.2785.116 Safari/537.36

Steps to reproduce the problem:
1. Write a Chrome extension. 
2. Attempt to use Chrome Apps "webview" tag API
3. Doesn't work.

What is the expected behavior?
Post deprecation of chrome Apps, let's get webview tag on extensions.

What went wrong?
The webview tag is not in the extension APIs. It must be.

WebStore page: 

Did this work before? Yes When  Chrome Apps were not on  death row.

Chrome version: 53.0.2785.116  Channel: stable
OS Version: 10.0
Flash Version: Shockwave Flash 23.0 r0

Webview tag is useful.