Always report the metric id even if the metric has no data to upload.

This is to normalize the metric when applying cross-device aggregation.

Test: statsd test
BUG: b/118203108

Change-Id: I644a6a4163e2d2ad8f70e0c4e002dd4f542248af
diff --git a/cmds/statsd/src/metrics/MetricProducer.h b/cmds/statsd/src/metrics/MetricProducer.h
index 127cbbd..09e2409 100644
--- a/cmds/statsd/src/metrics/MetricProducer.h
+++ b/cmds/statsd/src/metrics/MetricProducer.h
@@ -223,6 +223,10 @@
 
     void activateLocked(int activationTrackerIndex, int64_t elapsedTimestampNs);
 
+    inline bool isActiveLocked() const {
+        return mIsActive;
+    }
+
     /**
      * Flushes the current bucket if the eventTime is after the current bucket's end time. This will
        also flush the current partial bucket in memory.