UserAgent: Mozilla/5.0 (Macintosh; Intel Mac OS X 10_13_6) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/68.0.3440.25 Safari/537.36

Steps to reproduce the problem:
Not a problem, request for a new feature.

What is the expected behavior?
Passing the flags as follows:

chromium-browser --headless --screenshot --window-size=1440,1200 --full-page

Should have the effect of setting the viewport size to 1440x1200 initially, but if the page is longer than 1200px, it should screenshot the full page instead, exactly like puppeteer's fullPage option in the screenshot API.

This API would prove incredibly useful for general screenshot testing, and for web archiving purposes here: https://github.com/pirate/bookmark-archiver

Current solutions require installing chromium via puppeteer and using its node API, instead of using already installed versions of chrome with CLI flags, which would be much simpler for many users.

What went wrong?
Not a problem, request for a new feature.

Did this work before? No 

Does this work in other browsers? N/A

Chrome version: 68.0.3440.25  Channel: beta
OS Version: OS X 10.13.6
Flash Version: