Examine source code of Leads-Tracker-VanillaJS

{
  "manifest_version": 2,
  "version": "1.0",
  "name": "Leads Tracker",
  "browser_action": {
    "default_popup": "index.html",
    "default_icon": "icon_leads_tracker.png"
  },
  "permissions": [
    "tabs"
  ],
  "browser_specific_settings": {
    "gecko": {
      "id": "{3c190572-6ba8-4209-a0d4-2c47744d2fa3}"
    }
  }
}