Examine source code of Character Word Counter

{
  "manifest_version": 3,
  "name": "Character Word Counter",
  "version": "1.0.1",
  "description": "Counts words per character in scripts. Names must be uppercase, followed by a colon; replies separated by an empty line.",
  "permissions": [
    "activeTab",
    "scripting"
  ],
  "action": {
    "default_popup": "popup.html",
    "default_icon": {
      "16": "images/icon16.png",
      "48": "images/icon48.png",
      "128": "images/icon128.png"
    }
  },
  "icons": {
    "16": "images/icon16.png",
    "48": "images/icon48.png",
    "128": "images/icon128.png"
  },
  "host_permissions": [
    "<all_urls>"
  ],
  "browser_specific_settings": {
    "gecko": {
      "id": "character-word-counter@tommyholmberg.com"
    }
  }
}