Examine source code of PHPNav

{
  "manifest_version": 2,
  "name": "PHP Doc Arrow Key Navigation",
  "version": "0.1",
  "applications": {
    "gecko": {
      "id": "ahmetelgn@gmail.com"
    }
  },
  "description": "Navigate with arrow keys in PHP Documentation",
  "icons": {
    "48": "php_logo.png"
  },
  "content_scripts": [
    {
      "matches": [
        "*://www.php.net/manual/*"
      ],
      "js": [
        "src.js"
      ]
    }
  ]
}