Examine source code of Voltar Aba Fechada

{
  "manifest_version": 2,
  "name": "Voltar Aba Fechada",
  "version": "1.0",
  "background": {
    "persistent": true,
    "scripts": [
      "common.js",
      "bg.js"
    ]
  },
  "content_scripts": [
    {
      "matches": [
        "<all_urls>"
      ],
      "js": [
        "turnb.js"
      ]
    }
  ],
  "browser_action": {
    "default_icon": {
      "19": "icon-19-0.png",
      "38": "icon-38-0.png"
    },
    "default_popup": "popup.html",
    "default_title": "__MSG_manifest_toolbarbtn_tooltip__"
  },
  "commands": {
    "undo-latest": {
      "description": "__MSG_manifest_kbshort1__",
      "suggested_key": {
        "default": "Alt+Z",
        "mac": "MacCtrl+Z"
      }
    }
  },
  "options_ui": {
    "page": "options.html"
  },
  "default_locale": "pt_BR",
  "description": "__MSG_manifest_description__",
  "icons": {
    "16": "icon-16.png",
    "48": "icon-48.png",
    "128": "icon-128.png"
  },
  "permissions": [
    "tabs",
    "unlimitedStorage",
    "storage",
    "<all_urls>",
    "webRequest",
    "webRequestBlocking"
  ]
}