Add support for deep audio buffers

Allow AudioSink to use deep audio buffering when the
source is audio only and its duration is more than
a certain threshold.
This helps improve battery life but implies higher
audio latency.

Change-Id: Ie79915b61c370292f05aabda9779356570e03cbb
diff --git a/media/libmedia/AudioTrack.cpp b/media/libmedia/AudioTrack.cpp
index 092b516..25d79d6 100644
--- a/media/libmedia/AudioTrack.cpp
+++ b/media/libmedia/AudioTrack.cpp
@@ -225,6 +225,10 @@
         flags = (audio_output_flags_t)
                 ((flags | AUDIO_OUTPUT_FLAG_DIRECT) & ~AUDIO_OUTPUT_FLAG_FAST);
     }
+    // only allow deep buffering for music stream type
+    if (streamType != AUDIO_STREAM_MUSIC) {
+        flags = (audio_output_flags_t)(flags &~AUDIO_OUTPUT_FLAG_DEEP_BUFFER);
+    }
 
     if (!audio_is_output_channel(channelMask)) {
         ALOGE("Invalid channel mask");