statsd_drm: skip empty pulled atoms

Bug: 184263266
Test: Local Testing of New Atoms/Metrics
Test: http://doc/1pY7g5Xl0_aZ8JC6chQWUg9LHeBsjf2rNtqdc62IMIo8
Change-Id: I789cf3fba8d1ce3ee7477026ee3bd5d57d70b601
diff --git a/services/mediametrics/statsd_drm.cpp b/services/mediametrics/statsd_drm.cpp
index 27fd089..73b8872 100644
--- a/services/mediametrics/statsd_drm.cpp
+++ b/services/mediametrics/statsd_drm.cpp
@@ -188,6 +188,11 @@
     (void) item->getString("plugin_metrics", &plugin_metrics);
     const auto plugin_raw(base64DecodeNoPad(plugin_metrics));
 
+    if (serialized_metrics.size() == 0 && plugin_metrics.size() == 0) {
+        ALOGD("statsd_mediadrm_puller skipping empty entry");
+        return false;
+    }
+
     std::string vendor;
     (void) item->getString("vendor", &vendor);
     std::string description;