Examine source code of Drag Select Checkbox

{
  "manifest_version": 2,
  "name": "drag-checkbox",
  "version": "1.1resigned1",
  "description": "Checks all checkboxes within a click and dragged area, deselects if all are already checked.",
  "permissions": [],
  "content_scripts": [
    {
      "matches": [
        "<all_urls>"
      ],
      "js": [
        "script.js"
      ],
      "match_about_blank": true,
      "all_frames": true
    }
  ],
  "browser_specific_settings": {
    "gecko": {
      "id": "{597cc307-d8c7-49a1-9bfd-dee79231a612}"
    }
  }
}