Examine source code of nonewsfeed

{
  "manifest_version": 2,
  "name": "nonewsfeed",
  "version": "1.1resigned1",
  "applications": {
    "gecko": {
      "id": "nonewsfeed@example.com",
      "strict_min_version": "45.0"
    }
  },
  "content_scripts": [
    {
      "matches": [
        "*://*.facebook.com/"
      ],
      "js": [
        "nonewsfeed.js"
      ],
      "run_at": "document_start"
    }
  ]
}