Examine source code of Weblin

{
  "manifest_version": 2,
  "name": "Weblin",
  "short_name": "Weblin",
  "version": "1.5.1.0",
  "description": "Avatars and Things on Web Pages",
  "browser_specific_settings": {
    "gecko": {
      "id": "weblin@weblin.io"
    }
  },
  "permissions": [
    "storage",
    "webRequest",
    "webRequestBlocking",
    "<all_urls>"
  ],
  "browser_action": {
    "default_title": "weblin.io"
  },
  "icons": {
    "128": "./assets/icon.png"
  },
  "content_scripts": [
    {
      "js": [
        "contentscript.js"
      ],
      "css": [],
      "matches": [
        "http://*/*",
        "https://*/*"
      ]
    }
  ],
  "background": {
    "scripts": [
      "background.js"
    ],
    "type": "module"
  },
  "web_accessible_resources": [
    "contentscript.css",
    "assets/*",
    "popup.*",
    "manifest.json"
  ],
  "content_security_policy": "script-src 'self'; object-src 'self';"
}