Examine source code of LastTab

{
  "manifest_version": 2,
  "name": "Reopen Browsing History",
  "version": "1.0",
  "description": "Reopen your browsing history with the shortcut Ctrl + Shift + T",
  "background": {
    "scripts": [
      "background.js"
    ]
  },
  "permissions": [
    "history"
  ],
  "commands": {
    "reopen-history": {
      "suggested_key": {
        "default": "Ctrl+Shift+T",
        "mac": "MacCtrl+Shift+T"
      },
      "description": "Reopen your last closed tab"
    }
  },
  "browser_specific_settings": {
    "gecko": {
      "id": "{35f9069d-4fc5-48bf-b348-b4d3e8212d3f}"
    }
  }
}