Examine source code of NewsBrief Extension

{
  "manifest_version": 2,
  "name": "NewsBrief Extension",
  "version": "1.0",
  "description": "Get a quick summary view of top news stories in your browser.",
  "icons": {
    "48": "icon.png"
  },
  "permissions": [
    "activeTab",
    "https://rss.cnn.com/rss/edition.rss",
    "https://feeds.bbci.co.uk/news/rss.xml"
  ],
  "browser_action": {
    "default_popup": "popup.html",
    "default_icon": "icon.png"
  },
  "browser_specific_settings": {
    "gecko": {
      "id": "{97ee0307-4760-4b4c-a8c2-caf099c10285}"
    }
  }
}