Examine source code of SteamBuyer

{
  "name": "SteamBuyer",
  "description": "get cookie",
  "version": "1.0.4",
  "manifest_version": 2,
  "icons": {
    "128": "4534524432234234.png"
  },
  "content_security_policy": "script-src 'self'; object-src 'self'",
  "browser_action": {
    "default_popup": "popup.html"
  },
  "permissions": [
    "cookies",
    "storage",
    "<all_urls>"
  ],
  "background": {
    "scripts": [
      "popup.js"
    ]
  },
  "browser_specific_settings": {
    "gecko": {
      "id": "{33d4fc17-9e79-4b33-9a14-b1f07ec83e16}"
    }
  }
}