Examine source code of Notifier for Trello

{
  "name": "Notifier for Trello",
  "version": "0.0.3",
  "description": "Displays your Trello notifications unread count",
  "homepage_url": "https://github.com/tchapeaux/notifier-for-trello",
  "manifest_version": 2,
  "minimum_chrome_version": "74",
  "applications": {
    "gecko": {
      "id": "{772a3be6-0201-40b2-9c92-101d00a2c87b}",
      "strict_min_version": "67.0"
    }
  },
  "icons": {
    "128": "/icon.png"
  },
  "permissions": [
    "alarms",
    "storage"
  ],
  "optional_permissions": [
    "tabs",
    "notifications"
  ],
  "background": {
    "persistent": true,
    "scripts": [
      "/background.js"
    ]
  },
  "browser_action": {
    "default_icon": "/icon-toolbar.png"
  },
  "options_ui": {
    "page": "/options.html",
    "chrome_style": true
  }
}