Examine source code of Rediscover RSS

{
  "manifest_version": 2,
  "name": "Detect RSS/Atom",
  "version": "1.0",
  "description": "Detects RSS/Atom feeds and displays a status bar with an import link.",
  "permissions": [
    "storage"
  ],
  "content_scripts": [
    {
      "matches": [
        "*://*/*"
      ],
      "js": [
        "detect-rss.js"
      ],
      "run_at": "document_idle"
    }
  ],
  "options_ui": {
    "page": "options.html",
    "open_in_tab": true
  },
  "browser_specific_settings": {
    "gecko": {
      "id": "detect-rss@techleads.com.br"
    }
  }
}