Removes redundant RefBase inheritance.

PackageInfoListener already inherits from RefBase, so the
MetricsProducer doesn't need it also.

Test: Not needed.
Change-Id: I27fc4c214251ba07fefeacf76549a80c8368ffa5

cmds/statsd/src/metrics/MetricProducer.h

@@ -30,7 +30,7 @@ namespace statsd {
 // writing the report to dropbox. MetricProducers should respond to package changes as required in
 // PackageInfoListener, but if none of the metrics are slicing by package name, then the update can
 // be a no-op.
-class MetricProducer : public virtual RefBase, public virtual PackageInfoListener {
+class MetricProducer : public virtual PackageInfoListener {
 public:
     virtual ~MetricProducer(){};