Examine source code of DA Checker

{
  "manifest_version": 2,
  "name": "DA Checker",
  "version": "1.0",
  "description": "Checks the Domain Authority of the current website.",
  "icons": {
    "48": "icon.png"
  },
  "permissions": [
    "activeTab",
    "https://moz.com/"
  ],
  "browser_action": {
    "default_icon": "icon.png",
    "default_popup": "popup/da_checker.html"
  },
  "browser_specific_settings": {
    "gecko": {
      "id": "{86fee05e-6957-48de-8b7d-b7eb2e3af318}"
    }
  }
}