Examine source code of uQrl

{
  "manifest_version": 2,
  "name": "uQrl",
  "version": "1.1resigned1",
  "description": "Convert all tabs' URLs in current window to QR code",
  "icons": {
    "48": "icons/logo-48.png",
    "96": "icons/logo-96.png"
  },
  "permissions": [
    "<all_urls>",
    "tabs"
  ],
  "browser_action": {
    "default_icon": "icons/logo-32.png",
    "default_title": "uQrl",
    "default_popup": "uQrl.html"
  },
  "browser_specific_settings": {
    "gecko": {
      "id": "{2269b804-fa66-4490-8ed9-cc445cf9788c}"
    }
  }
}