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

net/disk_cache/stats_histogram.cc

 // Copyright (c) 2011 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #include "net/disk_cache/stats_histogram.h"
 
+#include "base/debug/leak_annotations.h"
 #include "base/logging.h"
 #include "net/disk_cache/stats.h"
 
 namespace disk_cache {
 
 using base::Histogram;
 using base::StatisticsRecorder;
 
 // Static.
 const Stats* StatsHistogram::stats_ = NULL;
 
 StatsHistogram::~StatsHistogram() {
   // Only cleanup what we set.
   if (init_)
     stats_ = NULL;
 }
 
-StatsHistogram* StatsHistogram::StatsHistogramFactoryGet(
-    const std::string& name) {
+StatsHistogram* StatsHistogram::FactoryGet(const std::string& name) {
   Histogram* histogram(NULL);
 
   Sample minimum = 1;
   Sample maximum = disk_cache::Stats::kDataSizesLength - 1;
   size_t bucket_count = disk_cache::Stats::kDataSizesLength;
 
   if (StatisticsRecorder::FindHistogram(name, &histogram)) {
     DCHECK(histogram != NULL);
   } else {
     // To avoid racy destruction at shutdown, the following will be leaked.
     StatsHistogram* stats_histogram =
         new StatsHistogram(name, minimum, maximum, bucket_count);
     stats_histogram->InitializeBucketRange();
     stats_histogram->SetFlags(kUmaTargetedHistogramFlag);
     histogram = StatisticsRecorder::RegisterOrDeleteDuplicate(stats_histogram);
+    if (histogram == stats_histogram)
+        ANNOTATE_LEAKING_OBJECT_PTR(return_histogram); // see crbug.com/79322
   }
 
   DCHECK(HISTOGRAM == histogram->histogram_type());
   DCHECK(histogram->HasConstructorArguments(minimum, maximum, bucket_count));
 
   // We're preparing for an otherwise unsafe upcast by ensuring we have the
   // proper class type.
   StatsHistogram* return_histogram = static_cast<StatsHistogram*>(histogram);
   // Validate upcast by seeing that we're probably providing the checksum.
   CHECK_EQ(return_histogram->StatsHistogram::CalculateRangeChecksum(),
@@ skipping 38 matching lines @@
   return NO_INCONSISTENCIES;  // This class won't monitor inconsistencies.
 }
 
 uint32 StatsHistogram::CalculateRangeChecksum() const {
   // We don't calculate checksums, so at least establish a unique constant.
   const uint32 kStatsHistogramChecksum = 0x0cecce;
   return kStatsHistogramChecksum;
 }
 
 }  // namespace disk_cache