As of Chrome 20, the request methods on the tabs and extension API have been deprecated in favour of message methods.
For future compatibility I want to migrate all instances of sendRequest, onRequest, and onRequestExternal to sendMessage, onMessage, and onMessageExternal respectively.
It's also worth noting that onMessage and onMessageExternal behave differently if the event handler returns true so it might be worth checking the current code.
Finally, I'd like to know when onMessage was introduced in case the minimum Chrome version needs to be increased in the manifest.
It might also be good to integrate the new runtime API into the utils namespace which will fall back on old/workaround functionality (e.g. extension ID, getting manifest). This API was added in Chrome 22.
#122 delivered these changes for message-related API methods only and not the others as previously suggested as it's simply not required and provides little to no benefit.