Examine source code of osu! PP Calculator

{
  "name": "osu! PP calculator",
  "version": "1.0.3",
  "description": "Calculates pp values for osu! beatmaps page.",
  "manifest_version": 3,
  "author": "Glean",
  "action": {
    "default_popup": "popup.html",
    "default_title": "Beatmap PP",
    "default_icon": {
      "16": "images/icon-16.png",
      "32": "images/icon-32.png"
    }
  },
  "browser_specific_settings": {
    "gecko": {
      "id": "{0b188aef-cdb9-4630-ac45-fd7971ef4049}"
    }
  },
  "icons": {
    "16": "images/icon-16.png",
    "32": "images/icon-32.png",
    "48": "images/icon-48.png",
    "128": "images/icon-128.png"
  },
  "permissions": [
    "storage",
    "activeTab"
  ]
}