Examine source code of RealmEye Helper

{
  "manifest_version": 2,
  "name": "RealmEye Helper",
  "version": "1.0.1",
  "description": "Adds \"Copy whisper\" buttons to RealmEye's offers pages.",
  "content_scripts": [
    {
      "matches": [
        "*://www.realmeye.com/offers-to/*"
      ],
      "js": [
        "copywhisper.js"
      ]
    }
  ]
}