Examine source code of My Public IP

{
  "manifest_version": 2,
  "name": "MY Public IP",
  "version": "1.3",
  "description": "A simple extension that displays the current public IP Address of the user.",
  "permissions": [
    "webRequest",
    "webRequestBlocking",
    "storage",
    "activeTab"
  ],
  "browser_action": {
    "default_icon": "ipicon.png",
    "default_popup": "popup.html"
  },
  "browser_specific_settings": {
    "gecko": {
      "id": "charleysmithwth@gmail.com",
      "strict_min_version": "57.0"
    }
  },
  "background": {
    "scripts": [
      "background.js"
    ],
    "persistent": false
  },
  "icons": {
    "64": "ipicon.png"
  },
  "content_scripts": [
    {
      "matches": [
        "<all_urls>"
      ],
      "js": [
        "content.js"
      ]
    }
  ]
}