Examine source code of Gmail Quick Links

{
  "manifest_version": 2,
  "name": "Gmail Quick Links",
  "version": "0.3.21",
  "description": "a replacement for Gmail Quick Links",
  "short_name": "Gmail Links",
  "icons": {
    "16": "./assets/icon16.png",
    "48": "./assets/icon48.png",
    "128": "./assets/icon48.png"
  },
  "author": "Kevin Wu <kevin.wu@gmail.com>",
  "homepage_url": "https://github.com/kevinwucodes/gmail-quick-links",
  "content_scripts": [
    {
      "matches": [
        "https://mail.google.com/*"
      ],
      "css": [
        "default.css"
      ],
      "js": [
        "react.js",
        "react-dom.js",
        "dist.gmailquicklinks.bundle.js"
      ],
      "run_at": "document_idle"
    }
  ],
  "permissions": [
    "storage"
  ]
}