Examine source code of Tab Session Masterww

{
  "short_name": "Tab Session Master",
  "manifest_version": 2,
  "name": "Tab Session Master",
  "default_locale": "en",
  "description": "Save and restore the state of windows and tabs. It also supports automatic backup your current session",
  "version": "1.2.2",
  "icons": {
    "16": "/images/logo-16.png",
    "48": "/images/logo-48.png",
    "128": "/images/logo-128.png"
  },
  "background": {
    "scripts": [
      "browser-polyfill.min.js",
      "ga.min.js",
      "background.min.js"
    ],
    "persistent": false
  },
  "browser_action": {
    "default_icon": "/images/logo-128.png",
    "default_title": "Tab Session Master"
  },
  "permissions": [
    "tabs",
    "storage",
    "contextMenus",
    "notifications",
    "alarms",
    "activeTab",
    "https://www.google-analytics.com/*"
  ],
  "optional_permissions": [
    "bookmarks"
  ],
  "content_security_policy": "script-src 'self'; object-src 'self'; img-src * data:;",
  "browser_specific_settings": {
    "gecko": {
      "id": "{e6d8fa31-d84c-4fc4-a009-617e3d74eb30}"
    }
  }
}