Examine source code of WCO Blocker

{
  "manifest_version": 2,
  "name": "WCO Blocker",
  "version": "1.0.0",
  "description": "Block the annoying 10 second nagscreen from all WCO websites.",
  "browser_specific_settings": {
    "gecko": {
      "id": "wcoblocker@madman38.github.io",
      "data_collection_permissions": {
        "required": [
          "none"
        ]
      }
    }
  },
  "icons": {
    "16": "icons/icon_16.png",
    "48": "icons/icon_48.png",
    "128": "icons/icon_128.png"
  },
  "browser_action": {
    "default_popup": "popup.html",
    "default_icon": "icons/icon_48.png"
  },
  "permissions": [
    "*://wcostream.com/*",
    "*://*.wcostream.com/*"
  ],
  "content_scripts": [
    {
      "matches": [
        "*://wcostream.com/*",
        "*://*.wcostream.com/*"
      ],
      "js": [
        "content.js"
      ],
      "run_at": "document_end",
      "all_frames": true
    }
  ]
}