Examine source code of History Master Pro

{
  "manifest_version": 2,
  "name": "History Master",
  "version": "1.0.0",
  "description": "Take control of your browser history with advanced features",
  "permissions": [
    "history",
    "storage",
    "downloads"
  ],
  "browser_action": {
    "default_popup": "popup.html"
  },
  "background": {
    "scripts": [
      "background.js"
    ]
  },
  "icons": {
    "16": "icon-16.png",
    "32": "icon-32.png",
    "48": "icon-48.png",
    "128": "icon-128.png"
  },
  "browser_specific_settings": {
    "gecko": {
      "id": "your-extension-id@historymaster.com",
      "strict_min_version": "58.0"
    }
  }
}