Examine source code of Fullwidth mess Linkedin

{
  "manifest_version": 2,
  "version": "1.0",
  "name": "Fullwidth messaging for Linkedin",
  "description": "[Browser extension] to elevate your Linkedin messages productivity, having a wider interface ✨",
  "permissions": [
    "tabs",
    "https://www.linkedin.com/messaging/thread/*"
  ],
  "browser_action": {
    "default_popup": "popup.html",
    "default_icon": "icon-default.png"
  },
  "icons": {
    "16": "icon-default.png",
    "48": "icon-default.png",
    "128": "icon-default.png"
  },
  "web_accessible_resources": [
    "icon-default.png",
    "popup.html",
    "styles.css"
  ],
  "content_scripts": [
    {
      "matches": [
        "https://www.linkedin.com/messaging/thread/*"
      ],
      "js": [
        "content.js"
      ],
      "css": [
        "styles.css"
      ]
    }
  ],
  "browser_specific_settings": {
    "gecko": {
      "id": "{1f5f9d4f-05b9-4628-96a9-58f6161275d5}"
    }
  }
}