Examine source code of Custom Element Counter

{
  "manifest_version": 2,
  "name": "Custom Element Counter",
  "version": "1.2.0",
  "description": "Count any DOM elements on any website using CSS selectors or XPath. Background auto‑refresh, toolbar badge, shadow DOM support.",
  "author": "Magoyor",
  "homepage_url": "https://github.com/Magoyor/custom-element-counter-addon",
  "browser_specific_settings": {
    "gecko": {
      "id": "{7ea2c70c-e6e8-4d54-847b-07bd150bcd88}",
      "strict_min_version": "142.0",
      "data_collection_permissions": {
        "required": [
          "none"
        ]
      }
    }
  },
  "permissions": [
    "storage",
    "activeTab",
    "<all_urls>"
  ],
  "content_scripts": [
    {
      "matches": [
        "<all_urls>"
      ],
      "js": [
        "content.js"
      ],
      "run_at": "document_idle"
    }
  ],
  "browser_action": {
    "default_title": "Custom Element Counter",
    "default_popup": "popup.html",
    "default_icon": "icons/icon.svg"
  },
  "background": {
    "scripts": [
      "background.js"
    ],
    "persistent": true
  },
  "icons": {
    "48": "icons/icon.svg"
  }
}