Chrome and Chrome OS allow developers to produce synthesized speech. This document is an overview of the relevant code and code structure around synthesized speech.
A brief outline of the flow from speech request to the resulting speech on any platform.
chrome.tts extension API
The chrome.tts extension API allows extensions to request speech across Windows, Mac or Chrome OS, using native speech synthesis.
Input to the extension is first processed in the TtsExtensionApi.
Web Speech API
The TtsControllerImpl (in content/) processes utterances and sends them to the correct output engine.
The TtsControllerDelegateImpl (in chrome/) provides chrome-specific functionality, including making use of user prefs in Chrome OS.
May differ by system, including Mac, Wind, Android, Arc++, and Chrome OS
In Chrome OS:
TtsControllerUnittest in content/browser/speech
TtsControllerDelegateImplUnittest in chrome/browser/speech
ArcTtsServiceUnittest for ARC++ voices