Examine source code of No X

{
  "manifest_version": 2,
  "name": "No X",
  "version": "1.0",
  "description": "Blocks all X.com pages from being loaded",
  "icons": {
    "48": "48.png",
    "96": "96.png"
  },
  "content_scripts": [
    {
      "matches": [
        "*://*.x.com/*"
      ],
      "js": [
        "closex.js"
      ]
    }
  ],
  "browser_specific_settings": {
    "gecko": {
      "id": "{042fa845-7740-4968-9838-9fa3aae4490d}"
    }
  }
}