Cuando intento comunicarme entre mi contenido y el script de fondo, obtengo los siguientes errores:

Port error: Could not establish connection. Receiving end does not exist.
Error in event handler for 'undefined': Cannot read property 'message' of undefined       
TypeError: Cannot read property 'message' of undefined

background.js

function onRequest(request, sender, callbackFunction) {
    console.log("Me (BS) became this Message:" + request.message);
    sendResponse({message: request.message})
};
chrome.extension.onRequest.addListener(onRequest);

streamcloud.js

function contactBackground(nachricht){
    chrome.extension.sendMessage({message: nachricht}, function(response) {
        console.log("The Background Script got the following Message: " + response.message);
    });
}

y mimanifest.json

{
  "name": "InstantWatch - Dev",
  "manifest_version": 2,
  "version": "0.7",
  "permissions": ["tabs", "http://*/", "https://*/"],
  "background": {
    "scripts": ["background.js"]
  },  
  "browser_action": {
    "default_title": "InstantWatch",
    "default_icon" : "icon.ico"
  },
  "content_scripts": [
    {
      "matches": ["http://*/*", "http://*/*"],
      "js": ["jquery.js", "streamcloud.js"]
    }
  ]
}

Encontré la solución para agregar una background_page: "background.html" con un background.html vacío, pero como background_page no es compatible desde manifest_version: 2, no puedo usar eso.