Fix http://codereview.chromium.org/6869009 to ignore an existing object exactly once and land the...

base/metrics/histogram.cc

Index: base/metrics/histogram.cc
===================================================================
--- base/metrics/histogram.cc	(revision 86987)
+++ base/metrics/histogram.cc	(working copy)
@@ -14,6 +14,7 @@
 #include <algorithm>
 #include <string>
 
+#include "base/debug/leak_annotations.h"
 #include "base/logging.h"
 #include "base/pickle.h"
 #include "base/stringprintf.h"
@@ -97,6 +98,8 @@
     tentative_histogram->SetFlags(flags);
     histogram =
         StatisticsRecorder::RegisterOrDeleteDuplicate(tentative_histogram);
+    if (histogram == tentative_histogram)
+        ANNOTATE_LEAKING_OBJECT_PTR(histogram);  // see crbug.com/79322
   }
 
   DCHECK_EQ(HISTOGRAM, histogram->histogram_type());
@@ -791,6 +794,8 @@
     tentative_histogram->SetFlags(flags);
     histogram =
         StatisticsRecorder::RegisterOrDeleteDuplicate(tentative_histogram);
+    if (histogram == tentative_histogram)
+        ANNOTATE_LEAKING_OBJECT_PTR(histogram);  // see crbug.com/79322
   }
 
   DCHECK_EQ(LINEAR_HISTOGRAM, histogram->histogram_type());
@@ -882,6 +887,8 @@
     tentative_histogram->SetFlags(flags);
     histogram =
         StatisticsRecorder::RegisterOrDeleteDuplicate(tentative_histogram);
+    if (histogram == tentative_histogram)
+        ANNOTATE_LEAKING_OBJECT_PTR(histogram);  // see crbug.com/79322
   }
 
   DCHECK_EQ(BOOLEAN_HISTOGRAM, histogram->histogram_type());
@@ -929,6 +936,8 @@
     tentative_histogram->SetFlags(flags);
     histogram =
         StatisticsRecorder::RegisterOrDeleteDuplicate(tentative_histogram);
+    if (histogram == tentative_histogram)
+        ANNOTATE_LEAKING_OBJECT_PTR(histogram);  // see crbug.com/79322
   }
 
   DCHECK_EQ(histogram->histogram_type(), CUSTOM_HISTOGRAM);