Examine source code of mustat-checker

{
  "manifest_version": 2,
  "name": "mustat-check",
  "version": "1.3resigned1",
  "permissions": [
    "activeTab",
    "contextMenus",
    "<all_urls>"
  ],
  "background": {
    "scripts": [
      "background.js"
    ]
  },
  "browser_specific_settings": {
    "gecko": {
      "id": "{9afad954-59a0-4c99-b6a1-2e4b05cd3b5c}"
    }
  }
}