MediaMetrics: Add AudioFlinger logging

Test: atest mediametrics_tests
Test: mediametrics dumpsys
Bug: 138583596
Change-Id: I2086c5a780744d409052fde4c5ebc1dc92d95ea8
diff --git a/services/audioflinger/AudioFlinger.h b/services/audioflinger/AudioFlinger.h
index d4e0ae2..a16fa94 100644
--- a/services/audioflinger/AudioFlinger.h
+++ b/services/audioflinger/AudioFlinger.h
@@ -952,6 +952,8 @@
     SimpleLog  mRejectedSetParameterLog;
     SimpleLog  mAppSetParameterLog;
     SimpleLog  mSystemSetParameterLog;
+
+    static inline constexpr const char *mMetricsId = AMEDIAMETRICS_KEY_AUDIO_FLINGER;
 };
 
 #undef INCLUDING_FROM_AUDIOFLINGER_H