Examine source code of AntiRickRoll

{
  "manifest_version": 2,
  "name": "AntiRickRoll",
  "description": "Never gonna rickroll you, never gonna let you get rickrolled.",
  "version": "1.7",
  "content_scripts": [
    {
      "js": [
        "background/content.js"
      ],
      "matches": [
        "https://*.youtube.com/*"
      ],
      "run_at": "document_start"
    }
  ],
  "web_accessible_resources": [
    "warn/warn.html"
  ],
  "permissions": [
    "storage"
  ],
  "browser_action": {
    "default_popup": "popup/index.html",
    "default_title": "AntiRickRoll"
  },
  "icons": {
    "16": "icons/icon16.png",
    "48": "icons/icon48.png",
    "128": "icons/icon128.png"
  },
  "browser_specific_settings": {
    "gecko": {
      "id": "{5f1ad9c1-371d-4b5a-9469-0a187d41c3e9}"
    }
  }
}