Examine source code of Text Selection Unblocker

{
  "manifest_version": 2,
  "name": "Text Selection Unblocker",
  "version": "1.0",
  "description": "Allows text selection by overriding user-select CSS property.",
  "permissions": [
    "activeTab"
  ],
  "content_scripts": [
    {
      "matches": [
        "<all_urls>"
      ],
      "js": [
        "script.js"
      ],
      "css": [
        "styles.css"
      ]
    }
  ],
  "icons": {
    "48": "icons/icon.svg"
  },
  "browser_specific_settings": {
    "gecko": {
      "id": "{44d5ee1f-5256-444f-a3b4-8289d70481ae}"
    }
  }
}