Examine source code of FlagMyIP

{
  "manifest_version": 2,
  "name": "FlagMyIP",
  "version": "1.3",
  "description": "Displays the flag of the country associated with your current IP address",
  "icons": {
    "16": "icons/icon-16.png",
    "32": "icons/icon-32.png",
    "48": "icons/icon-48.png",
    "64": "icons/icon-64.png",
    "96": "icons/icon-96.png"
  },
  "permissions": [
    "https://free.freeipapi.com/*"
  ],
  "browser_action": {
    "default_icon": {
      "16": "icons/icon-16.png",
      "32": "icons/icon-32.png",
      "48": "icons/icon-48.png",
      "64": "icons/icon-64.png",
      "96": "icons/icon-96.png"
    },
    "default_title": "Country Flag (click to update)"
  },
  "background": {
    "scripts": [
      "background.js"
    ]
  },
  "browser_specific_settings": {
    "gecko": {
      "id": "flagmyip@carmeloscandaliato.com"
    }
  }
}