Examine source code of Subtle Tab

{
  "name": "Subtle Tab",
  "description": "Personalized experience on new tabs for better productivity",
  "version": "0.0.18",
  "incognito": "spanning",
  "chrome_url_overrides": {
    "newtab": "index.html"
  },
  "background": {
    "scripts": [
      "subtle.js"
    ]
  },
  "permissions": [
    "geolocation",
    "http://*.subtletab.com/",
    "storage",
    "https://*.wunderlist.com/",
    "https://*.todoist.com/",
    "https://www.googleapis.com/",
    "unlimitedStorage"
  ],
  "applications": {
    "gecko": {
      "id": "subtle@subtletab.com",
      "strict_min_version": "56.0"
    }
  },
  "browser_action": {
    "default_title": "Subtle Tab",
    "default_icon": {
      "16": "images/icons/icon16.png",
      "48": "images/icons/icon48.png"
    }
  },
  "icons": {
    "16": "images/icons/icon16.png",
    "48": "images/icons/icon48.png",
    "128": "images/icons/icon128.png"
  },
  "chrome_settings_overrides": {
    "homepage": "index.html"
  },
  "content_security_policy": "script-src 'self'; object-src 'self'",
  "manifest_version": 2
}