Examine source code of Save Open Tabs

{
  "manifest_version": 2,
  "name": "Save Open Tabs",
  "version": "1.2.1",
  "description": "A firefox extension to save all open tabs",
  "icons": {
    "32": "icons/icon32.png",
    "48": "icons/icon48.png",
    "96": "icons/icon96.png",
    "128": "icons/icon128.png"
  },
  "browser_action": {
    "default_icon": "icons/icon32.png",
    "default_title": "Save Open Tabs",
    "default_popup": "popup/index.html"
  },
  "permissions": [
    "tabs",
    "storage"
  ]
}