Add tee sink to SpdifStreamOut

Test: enable per https://source.android.com/docs/core/audio/debugging
      play ac3 track via SpdifStreamOut using
      AudioTrackSurroundTest#testPlayAC3Bytes
      dumpsys media.audio_flinger and see .raw iec61937 wrapped
      file in /data/misc/audioserver.
Change-Id: I65ccd9d8a5b92ef7ffc87e081095d8f7332d8acb
diff --git a/services/audioflinger/datapath/SpdifStreamOut.cpp b/services/audioflinger/datapath/SpdifStreamOut.cpp
index 43e9c0c..6bc1f2d 100644
--- a/services/audioflinger/datapath/SpdifStreamOut.cpp
+++ b/services/audioflinger/datapath/SpdifStreamOut.cpp
@@ -17,6 +17,7 @@
 
 #define LOG_TAG "AudioFlinger"
 //#define LOG_NDEBUG 0
+#include "Configuration.h"
 #include <system/audio.h>
 #include <utils/Log.h>
 
@@ -96,6 +97,16 @@
 
     ALOGI("SpdifStreamOut::open() status = %d", status);
 
+#ifdef TEE_SINK
+    if (status == OK) {
+        // Don't use PCM 16-bit format to avoid WAV encoding IEC61937 data.
+        mTee.set(customConfig.sample_rate,
+                audio_channel_count_from_out_mask(customConfig.channel_mask),
+                AUDIO_FORMAT_IEC61937, NBAIO_Tee::TEE_FLAG_OUTPUT_THREAD);
+        mTee.setId(std::string("_") + std::to_string(handle) + "_D");
+    }
+#endif
+
     return status;
 }
 
@@ -113,7 +124,15 @@
 
 ssize_t SpdifStreamOut::writeDataBurst(const void* buffer, size_t bytes)
 {
-    return AudioStreamOut::write(buffer, bytes);
+    const ssize_t written = AudioStreamOut::write(buffer, bytes);
+
+#ifdef TEE_SINK
+    if (written > 0) {
+        mTee.write(reinterpret_cast<const char *>(buffer),
+                written / AudioStreamOut::getFrameSize());
+    }
+#endif
+    return written;
 }
 
 ssize_t SpdifStreamOut::write(const void* buffer, size_t numBytes)