Examine source code of NewTab Clean

{
  "manifest_version": 2,
  "name": "NewTab Clean",
  "version": "2.3.4",
  "description": "A very clean New Tab page addon.",
  "chrome_url_overrides": {
    "newtab": "index.html"
  },
  "browser_action": {
    "default_icon": "img/icon64.png",
    "default_popup": "popup.html"
  },
  "permissions": [
    "storage",
    "http://api.openweathermap.org/*",
    "http://opendata.fmi.fi/wfs/*"
  ],
  "icons": {
    "64": "img/icon64.png"
  },
  "browser_specific_settings": {
    "gecko": {
      "id": "deboocha@gmail.com",
      "strict_min_version": "42.0"
    }
  }
}