How do I display the HTML on the Chrome DevTools Page?

[Naoto Ono]

Hello, 

I'm a developer of ruby/debug for the part which connects to Chrome DevTools Frontend. Chrome DevTools Frontend is a wonderful tool. Thank you.

Now, I try to show the HTML on the left side of Chrome DevTools Frontend via Chrome DevTools Protocol as follows:

However, it doesn't work even though I inserted HTML to the Element through Chrome DevTools Protocol.

Any ideas?