AudioTrack: add support for compressed audio

Add support for compressed audio playback by use
of an AudioTrack attached to a direct output thread.

Bug: 9428304.

Change-Id: I4a61be9cf0e31003ca85935d6e0ee38ca8192e03
diff --git a/services/audioflinger/PlaybackTracks.h b/services/audioflinger/PlaybackTracks.h
index 6130084..79bdfe8 100644
--- a/services/audioflinger/PlaybackTracks.h
+++ b/services/audioflinger/PlaybackTracks.h
@@ -54,6 +54,7 @@
                 return mStreamType;
             }
             bool        isOffloaded() const { return (mFlags & IAudioFlinger::TRACK_OFFLOAD) != 0; }
+            bool        isDirect() const { return (mFlags & IAudioFlinger::TRACK_DIRECT) != 0; }
             status_t    setParameters(const String8& keyValuePairs);
             status_t    attachAuxEffect(int EffectId);
             void        setAuxBuffer(int EffectId, int32_t *buffer);