puppeteer/test/assets/simple-extension/manifest.json

{
  "name": "Simple extension",
  "version": "0.1",
  "background": {
    "scripts": ["index.js"]
  },
  "content_scripts": [{
    "matches": ["<all_urls>"],
    "css": [],
    "js": ["content-script.js"]
  }],
  "permissions": ["background", "activeTab"],
  "manifest_version": 2
}