Examine source code of CSS Exfil Protection

{
  "manifest_version": 2,
  "name": "CSS Exfil Protection",
  "version": "1.1.0",
  "description": "Guard against CSS data exfiltration attacks.",
  "content_security_policy": "script-src 'self'; object-src 'self'; style-src 'self'",
  "permissions": [
    "http://*/",
    "https://*/",
    "storage",
    "tabs"
  ],
  "homepage_url": "https://www.mike-gualtieri.com/css-exfil-vulnerability-tester",
  "icons": {
    "16": "icons/icon-16.png",
    "32": "icons/icon-32.png",
    "48": "icons/icon-48.png",
    "64": "icons/icon-64.png",
    "128": "icons/icon-128.png"
  },
  "browser_action": {
    "default_icon": {
      "48": "icons/icon-48.png"
    },
    "default_popup": "popup.html"
  },
  "options_ui": {
    "page": "popup.html",
    "chrome_style": true
  },
  "content_scripts": [
    {
      "js": [
        "content.js"
      ],
      "matches": [
        "<all_urls>"
      ],
      "all_frames": true,
      "run_at": "document_start"
    }
  ],
  "background": {
    "scripts": [
      "background.js"
    ]
  },
  "applications": {
    "gecko": {
      "id": "{7fc8ef53-24ec-4205-87a4-1e745953bb0d}"
    }
  }
}