Examine source code of Remove disabled attribute

{
  "manifest_version": 2,
  "name": "Remove-Disabled-Tag",
  "version": "0.1.3",
  "description": "Removes the 'disabled' HTML attribute of a selected element.",
  "icons": {
    "48": "eraser.png"
  },
  "content_scripts": [
    {
      "matches": [
        "<all_urls>"
      ],
      "js": [
        "remove-disable.js"
      ]
    }
  ],
  "background": {
    "scripts": [
      "remove-disable-background.js"
    ]
  },
  "permissions": [
    "menus",
    "activeTab"
  ],
  "browser_specific_settings": {
    "gecko": {
      "id": "{90ae5424-e017-4d19-9aab-6bbdfa552a8a}"
    }
  }
}