Document examples where a developer might use the APIs.

Test: mmma frameworks/base/
Bug: 35767714

Change-Id: I845db36869b84a18e79d7fe28f10031cfe836617
diff --git a/core/java/android/speech/tts/SynthesisCallback.java b/core/java/android/speech/tts/SynthesisCallback.java
index e535cfa..f5e5f4d 100644
--- a/core/java/android/speech/tts/SynthesisCallback.java
+++ b/core/java/android/speech/tts/SynthesisCallback.java
@@ -151,6 +151,9 @@
      * listener ({@link UtteranceProgressListener#onRangeStart}) at the moment that frame has been
      * reached by the playback head.
      *
+     * <p>This information can be used by the client, for example, to highlight ranges of the text
+     * while it is spoken.
+     *
      * <p>The markerInFrames is a frame index into the audio for this synthesis request, i.e. into
      * the concatenation of the audio bytes sent to audioAvailable for this synthesis request. The
      * definition of a frame depends on the format given by {@link #start}. See {@link AudioFormat}
diff --git a/core/java/android/speech/tts/UtteranceProgressListener.java b/core/java/android/speech/tts/UtteranceProgressListener.java
index 59ee8f3..ef81f12 100644
--- a/core/java/android/speech/tts/UtteranceProgressListener.java
+++ b/core/java/android/speech/tts/UtteranceProgressListener.java
@@ -128,6 +128,9 @@
      * <p>This method is called when the audio is expected to start playing on the speaker. Note
      * that this is different from {@link #onAudioAvailable} which is called as soon as the audio is
      * generated.
+
+     * <p>This information can be used, for example, to highlight ranges of the text while it is
+     * spoken.
      *
      * <p>Only called if the engine supplies timing information by calling {@link
      * SynthesisCallback#rangeStart(int, int, int)}.