chrome/common/extensions/docs/examples/api/ttsEngine/console_tts_engine/manifest.json

{
  "name": "Console TTS Engine",
  "manifest_version": 2,
  "version": "2.1",
  "description": "A \"silent\" TTS engine that prints text to a small window rather than synthesizing speech.",
  "permissions": ["ttsEngine", "tabs"],
  "background": {
    "persistent": false,
    "scripts": ["console_tts_engine.js"]
  },
  "tts_engine": {
    "voices": [
      {
        "voice_name": "Console",
        "event_types": ["start", "word", "sentence", "end"]
      }
    ]
  }
}