Examine source code of REx: Researcher Explorer

{
  "default_locale": "pt_BR",
  "manifest_version": 3,
  "browser_specific_settings": {
    "gecko": {
      "id": "rex-explorer@pconradjunior",
      "data_collection_permissions": {
        "required": [
          "none"
        ]
      }
    }
  },
  "name": "__MSG_appName__",
  "description": "__MSG_appDescription__",
  "version": "0.0.1",
  "icons": {
    "16": "icons/icon_16.png",
    "32": "icons/icon_32.png",
    "48": "icons/icon_48.png",
    "96": "icons/icon_96.png",
    "128": "icons/icon_128.png"
  },
  "action": {
    "default_popup": "about.html"
  },
  "permissions": [
    "activeTab",
    "scripting"
  ],
  "host_permissions": [
    "<all_urls>"
  ],
  "background": {
    "scripts": [
      "background.js"
    ]
  },
  "content_scripts": [
    {
      "matches": [
        "<all_urls>"
      ],
      "js": [
        "content.js"
      ],
      "css": [
        "popover.css"
      ],
      "run_at": "document_idle"
    }
  ],
  "web_accessible_resources": [
    {
      "resources": [
        "icons/*.png"
      ],
      "matches": [
        "<all_urls>"
      ]
    }
  ]
}