UserAgent: Mozilla/5.0 (Windows NT 10.0; Win64; x64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/56.0.2924.87 Safari/537.36

Steps to reproduce the problem:
1. Open DevTools
2. Try to edit manifest properties

What is the expected behavior?
Properties are editable with and I can see the changes live on my site, just like when I edit CSS.

What went wrong?
Properties are not editable.

Did this work before? No 

Chrome version: 56.0.2924.87  Channel: n/a
OS Version: 10.0
Flash Version: 

It'd be great to be able to edit the properties on the manifest pane. Here's a few notes:

- As it stands right now, changes in some properties would only be visible when connected to an Android device/emulator. (At least that's what I imagine). For example, I don't think background_color or theme_color are visualized in Chrome for Desktop.

- There are currently several properties that aren't shown at all, but being able to edit the dir and lang properties, if not all the spec's properties, would be useful.