Use factory to create histograms, and refcounts to track lifetimes...

net/disk_cache/stats.cc

Index: net/disk_cache/stats.cc
===================================================================
--- net/disk_cache/stats.cc	(revision 33932)
+++ net/disk_cache/stats.cc	(working copy)
@@ -138,7 +138,8 @@
         backend->ShouldReportAgain()) {
       // Stats may be reused when the cache is re-created, but we want only one
       // histogram at any given time.
-      size_histogram_.reset(new StatsHistogram("DiskCache.SizeStats"));
+      size_histogram_ =
+          StatsHistogram::StatsHistogramFactoryGet("DiskCache.SizeStats");
       size_histogram_->Init(this);
     }
   }