Especially about:loopconversation will need to support a number of APIs as defined in http://mxr.mozilla.org/mozilla-central/source/browser/base/content/content.js. Most notably 'ContentWebRTC.jsm' is quite important. I believe we're already OK here, but it doesn't hurt to verify. Please resolve this bug if appropriate.
Potentially relevant: bug 1153016
The chat window already uses content.js, but the toolbarbutton/panel does not. It's probably prudent to just get content.js into the panel content. Some of what is in tab-content.js may need a non-tabbrowser version for these panels when moving them to e10s.
We've got enough working now to know that we don't need this now.