Examine source code of Simple Session Manager

{
  "manifest_version": 2,
  "name": "Simple Session Manager",
  "author": "ynyk",
  "description": "Save browser tabs and restore them later",
  "version": "1.0.3",
  "applications": {
    "gecko": {
      "id": "session_manager_prod@ynyk",
      "strict_min_version": "59.0"
    }
  },
  "icons": {
    "32": "icons/tab-manager-32x32.png",
    "48": "icons/tab-manager-48x48.png",
    "64": "icons/tab-manager-64x64.png",
    "96": "icons/tab-manager-96x96.png"
  },
  "permissions": [
    "tabs",
    "storage"
  ],
  "background": {
    "scripts": [
      "lib/browser-polyfill.js",
      "background/env.js",
      "background/background.js"
    ]
  },
  "browser_action": {
    "default_icon": "icons/tab-manager-32x32.png",
    "default_title": "TabManager",
    "default_popup": "popup/popup.html",
    "browser_style": false
  },
  "web_accessible_resources": [
    "img/progress1.gif"
  ]
}