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

{
  "name": "page timing script injection",
  "version": "0.1",
  "manifest_version": 2,
  "description": "Tests that content scripts fire at each of the load timings",
  "content_scripts": [
    {
      "matches": ["*://*/*"],
      "js": ["document_start.js"],
      "run_at": "document_start"
    },
    {
      "matches": ["*://*/*"],
      "js": ["document_end.js"],
      "run_at": "document_end"
    },
    {
      "matches": ["*://*/*"],
      "js": ["document_idle.js"],
      "run_at": "document_idle"
    }
  ]
}