Examine source code of FBlock

{
  "manifest_version": 2,
  "name": "FBlock",
  "version": "1.1resigned1",
  "description": "Removes Facebook adds.",
  "icons": {
    "48": "icons/icon-48.png",
    "96": "icons/icon-96.png"
  },
  "content_scripts": [
    {
      "matches": [
        "*://*.facebook.com/*"
      ],
      "js": [
        "fblock.js"
      ]
    }
  ],
  "browser_specific_settings": {
    "gecko": {
      "id": "{312c7dad-cf08-4e02-a507-1294ec705ec6}"
    }
  }
}