Examine source code of DMFocus for X

{
  "manifest_version": 2,
  "name": "DMFocus for X",
  "version": "1.0.0",
  "description": "No tweets, no ads - just DM. Access X.com direct messages in a clean and simplified interface.",
  "author": "Korben",
  "homepage_url": "https://korben.info",
  "icons": {
    "48": "icons/icon-48.png",
    "96": "icons/icon-96.png"
  },
  "permissions": [
    "activeTab",
    "tabs",
    "*://*.x.com/*",
    "*://*.twitter.com/*"
  ],
  "browser_action": {
    "default_icon": {
      "48": "icons/icon-48.png",
      "96": "icons/icon-96.png"
    },
    "default_title": "DMFocus for X"
  },
  "background": {
    "scripts": [
      "js/background.js"
    ],
    "persistent": false
  },
  "content_scripts": [
    {
      "matches": [
        "*://*.x.com/messages*",
        "*://*.twitter.com/messages*"
      ],
      "css": [
        "css/content.css"
      ],
      "js": [
        "js/content.js"
      ]
    }
  ],
  "browser_specific_settings": {
    "gecko": {
      "id": "{046bfacb-e6ea-4ad0-8b04-1214ba643ac3}"
    }
  }
}