Use lock-free lazy initialization for static histogram references

chrome/renderer/render_thread.cc

Index: chrome/renderer/render_thread.cc
===================================================================
--- chrome/renderer/render_thread.cc	(revision 80382)
+++ chrome/renderer/render_thread.cc	(working copy)
@@ -798,13 +798,9 @@
     const char *name, int min, int max, size_t buckets) {
   if (min <= 0)
     min = 1;
-  scoped_refptr<base::Histogram> histogram = base::Histogram::FactoryGet(
+  base::Histogram* histogram = base::Histogram::FactoryGet(
       name, min, max, buckets, base::Histogram::kUmaTargetedHistogramFlag);
-  // We'll end up leaking these histograms, unless there is some code hiding in
-  // there to do the dec-ref.
-  // TODO(jar): Handle reference counting in webkit glue.
-  histogram->AddRef();
-  return histogram.get();
+  return histogram;
 }
 
 static void AddHistogramSample(void* hist, int sample) {