Examine source code of Unsubscribe Me

{
  "name": "Unsubscribe Me",
  "author": "Mackenzie Lee",
  "description": "One click extension that clicks 'unsubscribe' link in emails for you. Just open an email and click the icon to use.",
  "icons": {
    "48": "/images/unsub-128.png"
  },
  "action": {
    "default_icon": {
      "16": "/images/unsub-128.png",
      "24": "/images/unsub-128.png",
      "32": "/images/unsub-128.png",
      "48": "/images/unsub-128.png",
      "128": "/images/unsub-128.png"
    },
    "default_title": "Click to Unsubscribe Quickly"
  },
  "manifest_version": 3,
  "version": "0.6",
  "permissions": [
    "activeTab",
    "scripting"
  ],
  "background": {
    "scripts": [
      "scripts/background.js"
    ]
  },
  "browser_specific_settings": {
    "gecko": {
      "id": "mackenzie@mackenziedev.com"
    }
  }
}