Examine source code of ChessPieceSwitcher

{
  "description": "Switch around piece sprites on lichess and chess.com",
  "manifest_version": 2,
  "name": "ChessPieceSwitcher",
  "version": "1.2",
  "homepage_url": "https://github.com/oetherington/ChessPieceSwitcher",
  "icons": {
    "48": "icons/icon-48.png",
    "96": "icons/icon-96.png",
    "128": "icons/icon-128.png"
  },
  "permissions": [
    "activeTab"
  ],
  "browser_action": {
    "default_icon": "icons/icon-48.png",
    "default_title": "ChessPieceSwitcher",
    "default_popup": "popup/lps.html"
  }
}