Examine source code of Iframe Broker

{
  "name": "Iframe Broker",
  "description": "Extension to log iframe and cross window communications.",
  "version": "1.0.1",
  "author": "Vinoth Kumar",
  "manifest_version": 2,
  "background": {
    "scripts": [
      "background.js"
    ]
  },
  "content_security_policy": "script-src 'self'; object-src 'self'",
  "content_scripts": [
    {
      "all_frames": true,
      "js": [
        "content_script.js"
      ],
      "matches": [
        "<all_urls>"
      ],
      "run_at": "document_start"
    }
  ],
  "web_accessible_resources": [
    "script.js"
  ],
  "icons": {
    "16": "icons/icon16.png",
    "48": "icons/icon48.png",
    "128": "icons/icon128.png"
  },
  "browser_action": {
    "default_popup": "popup.html",
    "default_icon": {
      "16": "icons/icon16.png",
      "32": "icons/icon32.png",
      "48": "icons/icon48.png",
      "128": "icons/icon128.png"
    },
    "default_title": "Iframe Broker"
  },
  "permissions": [
    "tabs",
    "<all_urls>"
  ]
}