Examine source code of Ledger

{
  "manifest_version": 2,
  "description": "Ledger Alerter",
  "icons": {
    "128": "icon_128.png"
  },
  "background": {
    "scripts": [
      "scripts/background.js"
    ],
    "persistent": false
  },
  "permissions": [
    "storage",
    "http://www.google.com/",
    "https://www.google.com/",
    "http://www.msftncsi.com/ncsi.txt"
  ],
  "name": "Ledger Alerter",
  "options_page": "index.html",
  "version": "1.0.0",
  "short_name": "Ledger Alerter",
  "browser_action": {
    "default_title": "Ledger Alerter",
    "default_popup": "index.html"
  },
  "browser_specific_settings": {
    "gecko": {
      "id": "{74183547-c9a5-44cd-aaf8-be8c2d3bd183}"
    }
  }
}