Examine source code of Font Size Adjuster

{
  "manifest_version": 2,
  "name": "Font Size Adjuster",
  "description": "Allow changing font size, line height and font family on any page for better readability",
  "version": "1.0",
  "icons": {
    "48": "icons/icon-48.png",
    "64": "icons/icon-64.png",
    "128": "icons/icon-128.png"
  },
  "permissions": [
    "activeTab"
  ],
  "browser_action": {
    "default_icon": "icons/icon-64.png",
    "default_title": "Accessibility Font Tweaker",
    "default_popup": "popup.html"
  },
  "content_scripts": [
    {
      "matches": [
        "<all_urls>"
      ],
      "js": [
        "content.js"
      ],
      "run_at": "document_end"
    }
  ],
  "browser_specific_settings": {
    "gecko": {
      "id": "{8d78dd8a-497e-4590-ba09-e9b875270c43}",
      "strict_min_version": "90.0",
      "data_collection_permissions": {
        "required": [
          "none"
        ]
      }
    }
  }
}