Merge "Implement QUEUE_FLUSH and QUEUE_DESTROY addition modes."

core/java/android/speech/tts/AudioMessageParams.java

core/java/android/speech/tts/AudioPlaybackHandler.java

core/java/android/speech/tts/MessageParams.java

core/java/android/speech/tts/PlaybackSynthesisCallback.java

core/java/android/speech/tts/SilenceMessageParams.java

core/java/android/speech/tts/SynthesisMessageParams.java

core/java/android/speech/tts/TextToSpeechService.java