Add logging of written frame counts

Bug: 31591209
Change-Id: Ife5917aa65b02c3b0791dfe1975c70ccf58f9a75
(cherry picked from commit 2c45393d842a5d2968ef78fa7a08667efdf15f2a)
diff --git a/services/audioflinger/FastMixer.cpp b/services/audioflinger/FastMixer.cpp
index 01f3939..e41d7bc 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) {