message: explanation about sender
diff: @@ -22,10 +22,13 @@ const router = new Router();
  router.use("/v1", apiv1);
  router.use(undefined, apiv1);
  -export default function(message, sender, sendResponse) {
  +export default function(message, backgroundPage, sendResponse) {
  + // The sender is always the background page since he is the one listening to the event
  + // message.id is the external extension id
  if (message.uri) {
  - return router.run(message).then(sendResponse).catch(err => (
  + router.run(message).then(sendResponse).catch(err => (
  sendResponse({ error: err.message })
  ));
  + return true;
  }
  }
  