Examine source code of Count Pinned Tabs

{
  "description": "Adds a prefix to each window to count number of pinned tabs in it",
  "author": "MrOtherGuy",
  "manifest_version": 3,
  "name": "Count Pinned Tabs",
  "permissions": [],
  "version": "0.0.6",
  "background": {
    "scripts": [
      "background-script.js"
    ]
  },
  "browser_specific_settings": {
    "gecko": {
      "id": "countPinnedTabs@example.com",
      "strict_min_version": "110.0"
    }
  }
}