Remove typically unused local_metadata_ field.

base/metrics/histogram_samples.h

 // 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.
 
 #ifndef BASE_METRICS_HISTOGRAM_SAMPLES_H_
 #define BASE_METRICS_HISTOGRAM_SAMPLES_H_
 
 #include <stddef.h>
 #include <stdint.h>
 
@@ skipping 110 matching lines @@
     AtomicSingleSample single_sample;  // 32 bits
   };
 
   // Because structures held in persistent memory must be POD, there can be no
   // default constructor to clear the fields. This derived class exists just
   // to clear them when being allocated on the heap.
   struct BASE_EXPORT LocalMetadata : Metadata {
     LocalMetadata();
   };
 
-  explicit HistogramSamples(uint64_t id);
   HistogramSamples(uint64_t id, Metadata* meta);
   virtual ~HistogramSamples();
 
   virtual void Accumulate(HistogramBase::Sample value,
                           HistogramBase::Count count) = 0;
   virtual HistogramBase::Count GetCount(HistogramBase::Sample value) const = 0;
   virtual HistogramBase::Count TotalCount() const = 0;
 
   virtual void Add(const HistogramSamples& other);
 
@@ skipping 31 matching lines @@
                               size_t bucket);
 
   // Atomically adjust the sum and redundant-count.
   void IncreaseSumAndCount(int64_t sum, HistogramBase::Count count);
 
   AtomicSingleSample& single_sample() { return meta_->single_sample; }
   const AtomicSingleSample& single_sample() const {
     return meta_->single_sample;
   }
 
+  Metadata* meta() { return meta_; }
+
  private:
-  // In order to support histograms shared through an external memory segment,
-  // meta values may be the local storage or external storage depending on the
-  // wishes of the derived class.
-  LocalMetadata local_meta_;
   Metadata* meta_;
 
   DISALLOW_COPY_AND_ASSIGN(HistogramSamples);
 };
 
 class BASE_EXPORT SampleCountIterator {
  public:
   virtual ~SampleCountIterator();
 
   virtual bool Done() const = 0;
@@ skipping 43 matching lines @@
   // Information about the single value to return.
   const HistogramBase::Sample min_;
   const int64_t max_;
   const size_t bucket_index_;
   HistogramBase::Count count_;
 };
 
 }  // namespace base
 
 #endif  // BASE_METRICS_HISTOGRAM_SAMPLES_H_