Examine source code of tedditnav

{
  "manifest_version": 2,
  "name": "tedditnav",
  "version": "1.9",
  "description": "Keyboard navigation for teddit.net",
  "background": {
    "scripts": [
      "build/background.js"
    ]
  },
  "content_scripts": [
    {
      "matches": [
        "*://teddit.net/*"
      ],
      "js": [
        "build/tedditnav.js"
      ]
    }
  ],
  "options_ui": {
    "page": "build/options.html"
  },
  "permissions": [
    "storage"
  ],
  "browser_specific_settings": {
    "gecko": {
      "id": "tedditnav@twenty.com"
    }
  }
}