Examine source code of web3-to-butt

{
  "manifest_version": 2,
  "name": "web3-to-butt",
  "version": "1.0",
  "description": "Replaces the text 'web3' with 'my butt' (or some other reasonable-sounding variant).",
  "icons": {
    "16": "icon16.png",
    "48": "icon48.png",
    "128": "icon128.png"
  },
  "content_scripts": [
    {
      "matches": [
        "*://*/*"
      ],
      "js": [
        "content_script.js"
      ],
      "run_at": "document_idle"
    }
  ]
}