Add logging of written frame counts

Bug: 31591209
Change-Id: Ife5917aa65b02c3b0791dfe1975c70ccf58f9a75
diff --git a/services/audioflinger/FastMixer.cpp b/services/audioflinger/FastMixer.cpp
index b0780a4..93f7ce5 100644
--- a/services/audioflinger/FastMixer.cpp
+++ b/services/audioflinger/FastMixer.cpp
@@ -412,6 +412,7 @@
             }
             ftDump->mUnderruns = underruns;
             ftDump->mFramesReady = framesReady;
+            ftDump->mFramesWritten = trackFramesWritten;
         }
 
         if (anyEnabledTracks) {