Examine source code of newTabNewLife

{
  "manifest_version": 2,
  "name": "new Tab New Life",
  "version": "1.4.0",
  "description": "Firefox startup page",
  "author": "Erik Koci",
  "permissions": [],
  "chrome_url_overrides": {
    "newtab": "index.html"
  },
  "chrome_settings_overrides": {
    "homepage": "index.html"
  },
  "icons": {
    "16": "icon128.png",
    "48": "icon128.png",
    "128": "icon128.png"
  },
  "homepage_url": "https://github.com/kocierik/newTabnewLife",
  "browser_specific_settings": {
    "gecko": {
      "id": "{d631840d-daf6-4c0f-b5f0-bfec141d1484}"
    }
  }
}