Examine source code of WP Message Text Blur

{
  "manifest_version": 2,
  "name": "WP Message Text Blur",
  "short_name": "WP Message Text Blur",
  "version": "3.0.5",
  "description": "Blur whatsapp messages in chat preview",
  "icons": {
    "16": "icon_16.png",
    "48": "icon_48.png",
    "128": "icon_128.png"
  },
  "browser_specific_settings": {
    "gecko": {
      "id": "wtb@emreakkaya.org",
      "strict_min_version": "58.0"
    }
  },
  "content_scripts": [
    {
      "css": [
        "wtb.css"
      ],
      "matches": [
        "https://web.whatsapp.com/*"
      ]
    }
  ]
}