Examine source code of Link Status Redux

{
  "description": "__MSG_extensionDescription__",
  "manifest_version": 2,
  "default_locale": "en",
  "name": "Link Status Redux",
  "version": "3.21",
  "author": "Juha Aatrokoski",
  "icons": {
    "32": "icon.png"
  },
  "browser_specific_settings": {
    "gecko": {
      "id": "linkstatus@jha.iki.fi",
      "strict_min_version": "71.0"
    }
  },
  "permissions": [
    "bookmarks",
    "history",
    "storage",
    "tabs",
    "<all_urls>"
  ],
  "background": {
    "scripts": [
      "defaults.js",
      "iframe.js",
      "plurals.js",
      "background.js"
    ]
  },
  "content_scripts": [
    {
      "matches": [
        "<all_urls>"
      ],
      "js": [
        "iframe.js",
        "content.js"
      ],
      "run_at": "document_end",
      "match_about_blank": true,
      "all_frames": true
    }
  ],
  "options_ui": {
    "page": "options.html",
    "open_in_tab": true,
    "browser_style": true
  }
}