chromium/chrome/test/data/extensions/api_test/content_scripts/main_world_injections/manifest.json

{
  "manifest_version": 3,
  "name": "Main world content script test extension",
  "version": "0.1",
  "description": "Tests that scripts can be injected into the main world",
  "background": {
    "service_worker": "worker.js",
    "type": "module"
  },
  "permissions": ["scripting", "tabs"],
  "host_permissions": ["*://main.example/*", "*://isolated.example/*"],
  "content_scripts": [
    {
      "matches": ["*://main.example/*"],
      "js": ["change_title.js"],
      "world": "MAIN",
      "runAt": "document_end"
    }, {
      "matches": ["*://isolated.example/*"],
      "js": ["change_title.js"],
      "world": "ISOLATED",
      "runAt": "document_end"
    }
  ]
}