Examine source code of Link Domain Highlighter

{
  "manifest_version": 2,
  "name": "Link Domain Highlighter",
  "description": "Highlight external links in one color and internal links in another for instant domain awareness",
  "version": "1.1",
  "icons": {
    "64": "ico/64.png",
    "128": "ico/128.png"
  },
  "content_scripts": [
    {
      "matches": [
        "<all_urls>"
      ],
      "js": [
        "content.js"
      ],
      "run_at": "document_end"
    }
  ],
  "browser_specific_settings": {
    "gecko": {
      "id": "{f3e3bad0-22a2-4907-9427-7133ba1a0ca6}",
      "strict_min_version": "90.0"
    }
  }
}