I'm building an extension to integrate with Gmail and integrating with Gmail by injecting the gmail.js into the page context, as shown here: https://github.com/KartikTalwar/gmail-chrome-extension-boilerplate/blob/master/content.js
That seems to be the only obvious way to make use of some globals that Google is embedding on the page.
So now, I need to get back to some of the functionality of the extension. Under normal conditions (operating from a content script), I would send a message to the background script, but is that even possible from the context of the tab itself?