Examine source code of Anti-Rickroll

{
  "manifest_version": 2,
  "name": "Anti-Rickroll",
  "version": "1.2",
  "description": "Warns you of rickrolling links",
  "content_scripts": [
    {
      "matches": [
        "<all_urls>"
      ],
      "js": [
        "main.js"
      ]
    }
  ],
  "icons": {
    "48": "icons/Anti-Rickroll-48.png",
    "96": "icons/Anti-Rickroll-96.png"
  }
}