Examine source code of Nooperify

{
  "manifest_version": 2,
  "name": "Nooperify",
  "version": "1.1",
  "description": "Adds rel=\"noopener noreferrer\" to links.",
  "icons": {
    "48": "icons/icon-48.png"
  },
  "browser_action": {
    "default_icon": "icons/icon-48.png",
    "default_title": "Nooperify",
    "default_popup": "popup/popup.html"
  },
  "content_scripts": [
    {
      "matches": [
        "<all_urls>"
      ],
      "js": [
        "content_scripts/main.js"
      ]
    }
  ],
  "browser_specific_settings": {
    "gecko": {
      "id": "{a040f358-fcaf-4394-bea1-3b4e1c20be18}"
    }
  }
}