Make UMA stats creation available in the Java interface.

webrtc/system_wrappers/include/metrics.h

Index: webrtc/system_wrappers/include/metrics.h
diff --git a/webrtc/system_wrappers/include/metrics.h b/webrtc/system_wrappers/include/metrics.h
index 0fee344aa407ac295861ece924f56486b5fff553..dd518eedb60ee64fb29a22cfecac75e63fe24bf7 100644
--- a/webrtc/system_wrappers/include/metrics.h
+++ b/webrtc/system_wrappers/include/metrics.h
@@ -289,6 +289,9 @@ Histogram* HistogramFactoryGetEnumeration(
 void HistogramAdd(
     Histogram* histogram_pointer, const std::string& name, int sample);
 
+// Function for adding a |sample| to a histogram without checkking the name.
+void HistogramAdd(Histogram* histogram_pointer, int sample);
+
 }  // namespace metrics
 }  // namespace webrtc