Simple Chrome extension

background.js

chrome.tabs.onUpdated.addListener(function(tabId, changeInfo, tab) {
    if (changeInfo.status == 'complete') {
      console.log("Completed tab was loaded, injecting content.js");
      chrome.scripting.executeScript(
        {
          target: {tabId: tabId},
          files: ['content.js']
        }
      );
    }
  });
  

content.js

document.addEventListener('DOMContentLoaded', function() {
    console.log("content.js loaded");
});

// have also tried window.load, window.addEventListener(load), etc.

manifest.json

{
    "name": "Input Monitor",
    "version": "0.9",
    "manifest_version": 3,
    "permissions": [
      "scripting",
      "activeTab"
    ],
    "host_permissions": [
      "http://*/",
      "https://*/"
    ],
    "background": {
      "service_worker": "background.js"
    },
    "description": "A Chrome extension that monitors input boxes for keywords."
  }