Examine source code of Language Switcher

{
  "manifest_version": 2,
  "name": "Language Switcher",
  "version": "1.0",
  "description": "Quickly switch webpage language using Google Translate.",
  "permissions": [
    "contextMenus",
    "tabs"
  ],
  "background": {
    "scripts": [
      "background.js"
    ]
  },
  "icons": {
    "48": "icon.png"
  },
  "browser_specific_settings": {
    "gecko": {
      "id": "{bfd6205c-451d-4a5a-8fee-b5bb9343af82}"
    }
  }
}