Add Track Sink Format to AudioMixer

Track Sink Format now allows both AUDIO_FORMAT_PCM_FLOAT and
AUDIO_FORMAT_PCM_16_BIT (default).  The float case is not
enabled now.

Change-Id: Ibee70cab4725c8bc9905e49f1f9a9c2448f76e00
Signed-off-by: Andy Hung <hunga@google.com>
diff --git a/services/audioflinger/AudioMixer.h b/services/audioflinger/AudioMixer.h
index d286986..3355db4 100644
--- a/services/audioflinger/AudioMixer.h
+++ b/services/audioflinger/AudioMixer.h
@@ -77,6 +77,7 @@
         MAIN_BUFFER     = 0x4002,
         AUX_BUFFER      = 0x4003,
         DOWNMIX_TYPE    = 0X4004,
+        SINK_FORMAT     = 0x4005, // AUDIO_FORMAT_PCM_(FLOAT|16_BIT)
         // for target RESAMPLE
         SAMPLE_RATE     = 0x4100, // Configure sample rate conversion on this track name;
                                   // parameter 'value' is the new sample rate in Hz.
@@ -193,7 +194,9 @@
 
         int32_t     sessionId;
 
-        int32_t     padding[2];
+        audio_format_t mSinkFormat; // at this time: AUDIO_FORMAT_PCM_(FLOAT|16_BIT)
+
+        int32_t     padding[1];
 
         // 16-byte boundary