MediaMetrics: Add const correctness for items in service

Allows multithreaded use of items without lock.

Test: mediametrics dumpsys, atest mediametrics_tests
Bug: 138583596
Change-Id: Ieb901076b9acc33a89737b320a4fc8ce82f2608d
diff --git a/services/mediaanalytics/statsd_audiothread.cpp b/services/mediaanalytics/statsd_audiothread.cpp
index e9d6b17..e62899b 100644
--- a/services/mediaanalytics/statsd_audiothread.cpp
+++ b/services/mediaanalytics/statsd_audiothread.cpp
@@ -37,7 +37,7 @@
 
 namespace android {
 
-bool statsd_audiothread(MediaAnalyticsItem *item)
+bool statsd_audiothread(const MediaAnalyticsItem *item)
 {
     if (item == NULL) return false;