Revert 232412 "Implement Google network speech synthesis."

chrome/browser/resources/network_speech_synthesis/tts_extension.js

-// Copyright 2013 The Chromium Authors. All rights reserved.
-// Use of this source code is governed by a BSD-style license that can be
-// found in the LICENSE file.
-
-/**
- * @fileoverview
- * This is a component extension that implements a text-to-speech (TTS)
- * engine powered by Google's speech synthesis API.
- *
- * This is an "event page", so it's not loaded when the API isn't being used,
- * and doesn't waste resources. When a web page or web app makes a speech
- * request and the parameters match one of the voices in this extension's
- * manifest, it makes a request to Google's API using Chrome's private key
- * and plays the resulting speech using HTML5 audio.
- */
-
-/**
- * The main class for this extension. Adds listeners to
- * chrome.ttsEngine.onSpeak and chrome.ttsEngine.onStop and implements
- * them using Google's speech synthesis API.
- * @constructor
- */
-function TtsExtension() {}
-
-TtsExtension.prototype = {
-  /**
-   * The url prefix of the speech server, including static query
-   * parameters that don't change.
-   * @type {string}
-   * @const
-   * @private
-   */
-  SPEECH_SERVER_URL_:
-      'https://www.google.com/speech-api/v2/synthesize?' +
-      'enc=mpeg&client=chromium',
-
-  /**
-   * A mapping from language and gender to voice name, hardcoded for now
-   * until the speech synthesis server capabilities response provides this.
-   * The key of this map is of the form '<lang>-<gender>'.
-   * @type {Object.<string, string>}
-   * @private
-   */
-  LANG_AND_GENDER_TO_VOICE_NAME_: {
-    'en-gb-male': 'rjs',
-    'en-gb-female': 'fis',
-  },
-
-  /**
-   * The arguments passed to the onSpeak event handler for the utterance
-   * that's currently being spoken. Should be null when no object is
-   * pending.
-   *
-   * @type {?{utterance: string, options: Object, callback: Function}}
-   * @private
-   */
-  currentUtterance_: null,
-
-  /**
-   * The HTML5 audio element we use for playing the sound served by the
-   * speech server.
-   * @type {HTMLAudioElement}
-   * @private
-   */
-  audioElement_: null,
-
-  /**
-   * A mapping from voice name to language and gender, derived from the
-   * manifest file.  This is used in case the speech synthesis request
-   * specifies a voice name but doesn't specify a language code or gender.
-   * @type {Object.<string, {lang: string, gender: string}>}
-   * @private
-   */
-  voiceNameToLangAndGender_: {},
-
-  /**
-   * This is the main function called to initialize this extension.
-   * Initializes data structures and adds event listeners.
-   */
-  init: function() {
-    // Get voices from manifest.
-    var voices = chrome.app.getDetails().tts_engine.voices;
-    for (var i = 0; i < voices.length; i++) {
-      this.voiceNameToLangAndGender_[voices[i].voice_name] = {
-        lang: voices[i].lang,
-        gender: voices[i].gender
-      };
-    }
-
-    // Initialize the audio element and event listeners on it.
-    this.audioElement_ = document.createElement('audio');
-    document.body.appendChild(this.audioElement_);
-    this.audioElement_.addEventListener(
-        'ended', this.onStop_.bind(this), false);
-    this.audioElement_.addEventListener(
-        'canplaythrough', this.onStart_.bind(this), false);
-
-    // Install event listeners for the ttsEngine API.
-    chrome.ttsEngine.onSpeak.addListener(this.onSpeak_.bind(this));
-    chrome.ttsEngine.onStop.addListener(this.onStop_.bind(this));
-    chrome.ttsEngine.onPause.addListener(this.onPause_.bind(this));
-    chrome.ttsEngine.onResume.addListener(this.onResume_.bind(this));
-  },
-
-  /**
-   * Handler for the chrome.ttsEngine.onSpeak interface.
-   * Gets Chrome's Google API key and then uses it to generate a request
-   * url for the requested speech utterance. Sets that url as the source
-   * of the HTML5 audio element.
-   * @param {string} utterance The text to be spoken.
-   * @param {Object} options Options to control the speech, as defined
-   *     in the Chrome ttsEngine extension API.
-   * @private
-   */
-  onSpeak_: function(utterance, options, callback) {
-    // Truncate the utterance if it's too long. Both Chrome's tts
-    // extension api and the web speech api specify 32k as the
-    // maximum limit for an utterance.
-    if (utterance.length > 32768)
-      utterance = utterance.substr(0, 32768);
-
-    try {
-      // First, stop any pending audio.
-      this.onStop_();
-
-      this.currentUtterance_ = {
-        utterance: utterance,
-        options: options,
-        callback: callback
-      };
-
-      var lang = options.lang;
-      var gender = options.gender;
-      if (options.voiceName) {
-        lang = this.voiceNameToLangAndGender_[options.voiceName].lang;
-        gender = this.voiceNameToLangAndGender_[options.voiceName].gender;
-      }
-
-      // Look up the specific voice name for this language and gender.
-      // If it's not in the map, it doesn't matter - the language will
-      // be used directly. This is only used for languages where more
-      // than one gender is actually available.
-      var key = lang.toLowerCase() + '-' + gender;
-      var voiceName = this.LANG_AND_GENDER_TO_VOICE_NAME_[key];
-
-      var url = this.SPEECH_SERVER_URL_;
-      chrome.systemPrivate.getApiKey((function(key) {
-        url += '&key=' + key;
-        url += '&text=' + escape(utterance);
-        url += '&lang=' + lang.toLowerCase();
-
-        if (voiceName)
-          url += '&name=' + voiceName;
-
-        if (options.rate) {
-          // Input rate is between 0.1 and 10.0 with a default of 1.0.
-          // Output speed is between 0.0 and 1.0 with a default of 0.5.
-          url += '&speed=' + (options.rate / 2.0);
-        }
-
-        if (options.pitch) {
-          // Input pitch is between 0.0 and 2.0 with a default of 1.0.
-          // Output pitch is between 0.0 and 1.0 with a default of 0.5.
-          url += '&pitch=' + (options.pitch / 2.0);
-        }
-
-        // This begins loading the audio but does not play it.
-        // When enough of the audio has loaded to begin playback,
-        // the 'canplaythrough' handler will call this.onStart_,
-        // which sends a start event to the ttsEngine callback and
-        // then begins playing audio.
-        this.audioElement_.src = url;
-      }).bind(this));
-    } catch (err) {
-      console.error(String(err));
-      callback({
-        'type': 'error',
-        'errorMessage': String(err)
-      });
-      this.currentUtterance_ = null;
-    }
-  },
-
-  /**
-   * Handler for the chrome.ttsEngine.onStop interface.
-   * Called either when the ttsEngine API requests us to stop, or when
-   * we reach the end of the audio stream. Pause the audio element to
-   * silence it, and send a callback to the ttsEngine API to let it know
-   * that we've completed. Note that the ttsEngine API manages callback
-   * messages and will automatically replace the 'end' event with a
-   * more specific callback like 'interrupted' when sending it to the
-   * TTS client.
-   * @private
-   */
-  onStop_: function() {
-    if (this.currentUtterance_) {
-      this.audioElement_.pause();
-      this.currentUtterance_.callback({
-        'type': 'end',
-        'charIndex': this.currentUtterance_.utterance.length
-      });
-    }
-    this.currentUtterance_ = null;
-  },
-
-  /**
-   * Handler for the canplaythrough event on the audio element.
-   * Called when the audio element has buffered enough audio to begin
-   * playback. Send the 'start' event to the ttsEngine callback and
-   * then begin playing the audio element.
-   * @private
-   */
-  onStart_: function() {
-    if (this.currentUtterance_) {
-      if (this.currentUtterance_.options.volume !== undefined) {
-        // Both APIs use the same range for volume, between 0.0 and 1.0.
-        this.audioElement_.volume = this.currentUtterance_.options.volume;
-      }
-      this.audioElement_.play();
-      this.currentUtterance_.callback({
-          'type': 'start',
-          'charIndex': 0
-      });
-    }
-  },
-
-  /**
-   * Handler for the chrome.ttsEngine.onPause interface.
-   * Pauses audio if we're in the middle of an utterance.
-   * @private
-   */
-  onPause_: function() {
-    if (this.currentUtterance_) {
-      this.audioElement_.pause();
-    }
-  },
-
-  /**
-   * Handler for the chrome.ttsEngine.onPause interface.
-   * Resumes audio if we're in the middle of an utterance.
-   * @private
-   */
-  onResume_: function() {
-    if (this.currentUtterance_) {
-      this.audioElement_.play();
-    }
-  }
-
-};
-
-(new TtsExtension()).init();