Connect SparseHistogram with the rest of stats system

base/metrics/sparse_histogram.cc

 // Copyright (c) 2012 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 "base/metrics/sparse_histogram.h"
 
 #include "base/metrics/sample_map.h"
 #include "base/metrics/statistics_recorder.h"
 #include "base/pickle.h"
 #include "base/synchronization/lock.h"
 
 using std::map;
 using std::string;
 
 namespace base {
 
 typedef HistogramBase::Count Count;
 typedef HistogramBase::Sample Sample;
 
 // static
 HistogramBase* SparseHistogram::FactoryGet(const string& name, int32 flags) {
-  // TODO(kaiwang): Register and get SparseHistogram with StatisticsRecorder.
-  HistogramBase* histogram = new SparseHistogram(name);
-  histogram->SetFlags(flags);
+  HistogramBase* histogram = StatisticsRecorder::FindHistogram(name);
+
+  if (!histogram) {
+    // To avoid racy destruction at shutdown, the following will be leaked.
+    HistogramBase* tentative_histogram = new SparseHistogram(name);
+    tentative_histogram->SetFlags(flags);
+    histogram =
+        StatisticsRecorder::RegisterOrDeleteDuplicate(tentative_histogram);
+  }
+  DCHECK_EQ(SPARSE_HISTOGRAM, histogram->GetHistogramType());
   return histogram;
 }
 
 SparseHistogram::~SparseHistogram() {}
 
 HistogramType SparseHistogram::GetHistogramType() const {
   return SPARSE_HISTOGRAM;
 }
 
 bool SparseHistogram::HasConstructionArguments(Sample minimum,
@@ skipping 58 matching lines @@
 void SparseHistogram::GetParameters(DictionaryValue* params) const {
   // TODO(kaiwang): Implement. (See HistogramBase::WriteJSON.)
 }
 
 void SparseHistogram::GetCountAndBucketData(Count* count,
                                             ListValue* buckets) const {
   // TODO(kaiwang): Implement. (See HistogramBase::WriteJSON.)
 }
 
 }  // namespace base