add feature: GaugeMetricProducer now takes repeated list of fields
bug fix: GaugeMetricProducer now works better with pulled events.
unit test also includes GaugeMetricProducer_test

Test: unit test
Change-Id: Ic60f09342d14cfb107be2130d445b323a56909e0
diff --git a/cmds/statsd/Android.mk b/cmds/statsd/Android.mk
index addba8c..3e517bb 100644
--- a/cmds/statsd/Android.mk
+++ b/cmds/statsd/Android.mk
@@ -173,6 +173,7 @@
     tests/metrics/DurationMetricProducer_test.cpp \
     tests/metrics/EventMetricProducer_test.cpp \
     tests/metrics/ValueMetricProducer_test.cpp \
+    tests/metrics/GaugeMetricProducer_test.cpp \
     tests/guardrail/StatsdStats_test.cpp
 
 LOCAL_STATIC_LIBRARIES := \