MediaMetrics: Misc fixes

Remove unneeded headers from MediaMetricsItem.
Optimize map writes with emplace_hint.

Test: atest mediametrics_tests
Bug: 149850236
Change-Id: Ice6fddb8402a5ccbf1df6e6e02fa4aae4c1b42d5
diff --git a/media/libmediametrics/MediaMetricsItem.cpp b/media/libmediametrics/MediaMetricsItem.cpp
index 4371668..7cdbe5f 100644
--- a/media/libmediametrics/MediaMetricsItem.cpp
+++ b/media/libmediametrics/MediaMetricsItem.cpp
@@ -25,6 +25,7 @@
 #include <set>
 
 #include <binder/Parcel.h>
+#include <cutils/properties.h>
 #include <utils/Errors.h>
 #include <utils/Log.h>
 #include <utils/SortedVector.h>