Examine source code of Vergissmeinnicht

{
  "manifest_version": 2,
  "version": "1",
  "name": "Vergissmeinnicht",
  "description": "Automatically cleans up the history. All pages not visited within the last 30 days are removed.",
  "icons": {
    "16": "images/logo_16.png",
    "48": "images/logo_48.png",
    "128": "images/logo.png"
  },
  "background": {
    "scripts": [
      "main.js"
    ]
  },
  "permissions": [
    "history"
  ]
}