Examine source code of Memento Mori

{
  "name": "Memento Mori",
  "author": "mance-rah",
  "description": "Reminds the user of the brevity of life with every new tab.",
  "version": "1.0",
  "manifest_version": 2,
  "icons": {
    "16": "icons/age-16.png",
    "48": "icons/age-48.png",
    "128": "icons/age-128.png"
  },
  "permissions": [
    "storage"
  ],
  "chrome_url_overrides": {
    "newtab": "newtab.html"
  },
  "web_accessible_resources": [
    "icons/*",
    "css/*"
  ]
}