extensions/test/data/api_test/audio/volume_change/manifest.json

{
  "name": "chrome.audio.OnOutputNodeVolumeChanged",
  "manifest_version": 2,
  "version": "1.0",
  "description": "browser test for chrome.audio.OnOutputNodeVolumeChanged event",
  "app": {
    "background": {
      "scripts": ["background.js"]
    }
  },
  "permissions": [
    "audio"
  ]
}