Disable TTS preview play button while playback is in progress.

Bug: 910082
Change-Id: Ic3469bf58361ceafd39cc39bfc84450caa801dbb
Reviewed-on: https://chromium-review.googlesource.com/c/1356232Reviewed-by: Hector Carmona <hcarmona@chromium.org>
Reviewed-by: David Tseng <dtseng@chromium.org>
Commit-Queue: Katie Dektar <katie@chromium.org>
Cr-Commit-Position: refs/heads/master@{#612833}

chrome/browser/resources/settings/a11y_page/tts_subpage.html

@@ -89,7 +89,8 @@
     <div class="settings-box continuation">
       <cr-input id="previewInput" label="$i18n{textToSpeechPreviewInputLabel}"
           value="$i18n{textToSpeechPreviewInput}">
-        <paper-button on-click="onPreviewTtsClick_" disabled="[[!hasVoices]]"
+        <paper-button on-click="onPreviewTtsClick_"
+            disabled="[[!enablePreviewButton_(allVoices, isPreviewing_)]]"
             slot="suffix">
           $i18n{textToSpeechPreviewPlay}
         </paper-button>

chrome/browser/resources/settings/a11y_page/tts_subpage.js

@@ -49,6 +49,15 @@ Polymer({
       notify: true,
     },
 
+    /**
+     * Whether preview is currently speaking.
+     * @private
+     */
+    isPreviewing_: {
+      type: Boolean,
+      value: false,
+    },
+
     /** Whether any voices are loaded. */
     hasVoices: {
       type: Boolean,
@@ -69,6 +78,8 @@ Polymer({
     chrome.send('getAllTtsVoiceData');
     this.addWebUIListener(
         'tts-extensions-updated', this.populateExtensionList_.bind(this));
+    this.addWebUIListener(
+        'tts-preview-state-changed', this.onTtsPreviewStateChanged_.bind(this));
     chrome.send('getTtsExtensions');
   },
 
@@ -137,6 +148,17 @@ Polymer({
     return voices.length > 0;
   },
 
+  /**
+   * Returns true if voices are loaded and preview is not currently speaking.
+   * @param {!Array<TtsHandlerVoice>} voices
+   * @param {boolean} isPreviewing
+   * @return {boolean}
+   * @private
+   */
+  enablePreviewButton_: function(voices, isPreviewing) {
+    return this.hasVoices_(voices) && !isPreviewing;
+  },
+
   /**
    * Populates the list of languages and voices for the UI to use in display.
    * @param {Array<TtsHandlerVoice>} voices
@@ -208,6 +230,16 @@ Polymer({
     this.extensions = extensions;
   },
 
+  /**
+   * Called when the TTS voice preview state changes between speaking and not
+   * speaking.
+   * @param {boolean} isSpeaking
+   * @private
+   */
+  onTtsPreviewStateChanged_: function(isSpeaking) {
+    this.isPreviewing_ = isSpeaking;
+  },
+
   /**
    * A function used for sorting languages alphabetically.
    * @param {Object} first A languageToVoices array item.

chrome/browser/ui/webui/settings/tts_handler.cc

@@ -108,6 +108,18 @@ void TtsHandler::OnVoicesChanged() {
   HandleGetTtsExtensions(nullptr);
 }
 
+void TtsHandler::OnTtsEvent(content::Utterance* utterance,
+                            content::TtsEventType event_type,
+                            int char_index,
+                            const std::string& error_message) {
+  if (event_type == content::TTS_EVENT_END ||
+      event_type == content::TTS_EVENT_INTERRUPTED ||
+      event_type == content::TTS_EVENT_ERROR) {
+    base::Value result(false /* preview stopped */);
+    FireWebUIListener("tts-preview-state-changed", result);
+  }
+}
+
 void TtsHandler::HandlePreviewTtsVoice(const base::ListValue* args) {
   DCHECK_EQ(2U, args->GetSize());
   std::string text;
@@ -131,8 +143,11 @@ void TtsHandler::HandlePreviewTtsVoice(const base::ListValue* args) {
   utterance->set_voice_name(name);
   utterance->set_extension_id(extension_id);
   utterance->set_src_url(GURL("chrome://settings/manageAccessibility/tts"));
-  utterance->set_event_delegate(nullptr);
+  utterance->set_event_delegate(this);
   content::TtsController::GetInstance()->Stop();
+
+  base::Value result(true /* preview started */);
+  FireWebUIListener("tts-preview-state-changed", result);
   content::TtsController::GetInstance()->SpeakOrEnqueue(utterance);
 }
 
@@ -159,6 +174,7 @@ void TtsHandler::OnJavascriptAllowed() {
 
 void TtsHandler::OnJavascriptDisallowed() {
   content::TtsController::GetInstance()->RemoveVoicesChangedDelegate(this);
+  content::TtsController::GetInstance()->RemoveUtteranceEventDelegate(this);
 }
 
 int TtsHandler::GetVoiceLangMatchScore(const content::VoiceData* voice,

chrome/browser/ui/webui/settings/tts_handler.h

@@ -15,7 +15,8 @@ namespace settings {
 
 // Chrome "/manageAccessibility/tts/*" settings page UI handler.
 class TtsHandler : public SettingsPageUIHandler,
-                   public content::VoicesChangedDelegate {
+                   public content::VoicesChangedDelegate,
+                   public content::UtteranceEventDelegate {
  public:
   TtsHandler();
   ~TtsHandler() override;
@@ -32,6 +33,12 @@ class TtsHandler : public SettingsPageUIHandler,
   // VoicesChangedDelegate implementation.
   void OnVoicesChanged() override;
 
+  // UtteranceEventDelegate implementation.
+  void OnTtsEvent(content::Utterance* utterance,
+                  content::TtsEventType event_type,
+                  int char_index,
+                  const std::string& error_message) override;
+
  private:
   void WakeTtsEngine(const base::ListValue* args);
   void OnTtsEngineAwake(bool success);