Examine source code of Copy Tabs URLs

{
  "manifest_version": 2,
  "name": "Copy Tabs URLs",
  "version": "1.0",
  "description": "Copy URLs of all open tabs to clipboard.",
  "icons": {
    "48": "icons/border-48.png"
  },
  "background": {
    "scripts": [
      "background.js"
    ]
  },
  "permissions": [
    "tabs",
    "clipboardWrite"
  ],
  "browser_action": {
    "default_icon": {
      "48": "icons/border-48.png"
    },
    "default_title": "Copy Tabs URLs"
  },
  "browser_specific_settings": {
    "gecko": {
      "id": "{817e18ec-a7a0-4202-b535-854cc9a7f112}"
    }
  }
}