Refactor of Histogram related code

net/disk_cache/stats_histogram.h

 // 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.
 
 #ifndef NET_DISK_CACHE_STATS_HISTOGRAM_H_
 #define NET_DISK_CACHE_STATS_HISTOGRAM_H_
 
 #include <string>
 
 #include "base/metrics/histogram.h"
@@ skipping 11 matching lines @@
 //
 class StatsHistogram : public base::Histogram {
  public:
   class StatsSamples : public SampleSet {
    public:
     Counts* GetCounts() {
       return &counts_;
     }
   };
 
-  StatsHistogram(const std::string& name, Sample minimum,
-                 Sample maximum, size_t bucket_count)
-      : Histogram(name, minimum, maximum, bucket_count), init_(false) {}
+  StatsHistogram(const std::string& name,
+                 Sample minimum,
+                 Sample maximum,
+                 size_t bucket_count)
+      : Histogram(name, minimum, maximum, bucket_count, NULL), init_(false) {}
   virtual ~StatsHistogram();
 
   static StatsHistogram* FactoryGet(const std::string& name);
 
   // We'll be reporting data from the given set of cache stats.
   bool Init(const Stats* stats);
 
   virtual Sample ranges(size_t i) const OVERRIDE;
   virtual size_t bucket_count() const OVERRIDE;
   virtual void SnapshotSample(SampleSet* sample) const OVERRIDE;
   virtual Inconsistencies FindCorruption(
       const SampleSet& snapshot) const OVERRIDE;
-  virtual uint32 CalculateRangeChecksum() const OVERRIDE;
 
  private:
   bool init_;
   static const Stats* stats_;
   DISALLOW_COPY_AND_ASSIGN(StatsHistogram);
 };
 
 }  // namespace disk_cache
 
 #endif  // NET_DISK_CACHE_STATS_HISTOGRAM_H_