Examine source code of やっぱり Noto Sans

{
  "manifest_version": 3,
  "name": "やっぱり Noto Sans",
  "version": "1.1.10",
  "description": "ウェブページ上の読みづらいフォントを、読みやすい Noto Sans に置き換えます。",
  "icons": {
    "16": "icons/icon-16x16.png",
    "48": "icons/icon-48x48.png",
    "128": "icons/icon-128x128.png"
  },
  "action": {
    "default_popup": "popup/popup.html"
  },
  "content_scripts": [
    {
      "matches": [
        "<all_urls>"
      ],
      "js": [
        "preload-fonts.js"
      ],
      "run_at": "document_idle"
    }
  ],
  "web_accessible_resources": [
    {
      "resources": [
        "fonts/*.woff2",
        "css/*.css"
      ],
      "matches": [
        "<all_urls>"
      ]
    }
  ],
  "browser_specific_settings": {
    "gecko": {
      "id": "{d5e9d1d8-7575-4b82-9c28-578b46b83cfc}"
    }
  }
}