Examine source code of ProtonDB on Steam

{
  "manifest_version": 2,
  "name": "ProtonDB status on Steam",
  "version": "0.1.0",
  "author": "Vegard Berg",
  "icons": {
    "48": "proton_48.png",
    "64": "proton_64.png",
    "96": "proton_96.png",
    "128": "proton_128.png"
  },
  "content_scripts": [
    {
      "matches": [
        "*://store.steampowered.com/app/*"
      ],
      "js": [
        "script.js"
      ],
      "css": [
        "style.css"
      ]
    }
  ],
  "permissions": [
    "*://*.protondb.com/*",
    "*://*.steampowered.com/*",
    "webRequest"
  ]
}