[UMA] Remove redundant bucket_count variable from base::Histogram.

base/metrics/histogram.h

Index: base/metrics/histogram.h
diff --git a/base/metrics/histogram.h b/base/metrics/histogram.h
index 72da2e0415ffed6dfd190dd64cfdd64b5ac9cc02..033cb72cf067464d29683017f6130806327b70cc 100644
--- a/base/metrics/histogram.h
+++ b/base/metrics/histogram.h
@@ -396,7 +396,6 @@ class BASE_EXPORT Histogram : public HistogramBase {
 
   static void InitializeBucketRanges(Sample minimum,
                                      Sample maximum,
-                                     size_t bucket_count,
                                      BucketRanges* ranges);
 
   // This constant if for FindCorruption. Since snapshots of histograms are
@@ -437,9 +436,10 @@ class BASE_EXPORT Histogram : public HistogramBase {
 
   // HistogramBase implementation:
   virtual HistogramType GetHistogramType() const OVERRIDE;
-  virtual bool HasConstructionArguments(Sample minimum,
-                                        Sample maximum,
-                                        size_t bucket_count) const OVERRIDE;
+  virtual bool HasConstructionArguments(
+      Sample expected_minimum,
+      Sample expected_maximum,
+      size_t expected_bucket_count) const OVERRIDE;
   virtual void Add(Sample value) OVERRIDE;
   virtual scoped_ptr<HistogramSamples> SnapshotSamples() const OVERRIDE;
   virtual void AddSamples(const HistogramSamples& samples) OVERRIDE;
@@ -448,12 +448,11 @@ class BASE_EXPORT Histogram : public HistogramBase {
   virtual void WriteAscii(std::string* output) const OVERRIDE;
 
  protected:
-  // |bucket_count| and |ranges| should contain the underflow and overflow
-  // buckets. See top comments for example.
+  // |ranges| should contain the underflow and overflow buckets. See top
+  // comments for example.
   Histogram(const std::string& name,
             Sample minimum,
             Sample maximum,
-            size_t bucket_count,
             const BucketRanges* ranges);
 
   virtual ~Histogram();
@@ -521,9 +520,8 @@ class BASE_EXPORT Histogram : public HistogramBase {
   // Does not own this object. Should get from StatisticsRecorder.
   const BucketRanges* bucket_ranges_;
 
-  Sample declared_min_;  // Less than this goes into counts_[0]
-  Sample declared_max_;  // Over this goes into counts_[bucket_count_ - 1].
-  size_t bucket_count_;  // Dimension of counts_[].
+  Sample declared_min_;  // Less than this goes into the first bucket.
+  Sample declared_max_;  // Over this goes into the last bucket.
 
   // Finally, provide the state that changes with the addition of each new
   // sample.
@@ -573,7 +571,6 @@ class BASE_EXPORT LinearHistogram : public Histogram {
 
   static void InitializeBucketRanges(Sample minimum,
                                      Sample maximum,
-                                     size_t bucket_count,
                                      BucketRanges* ranges);
 
   // Overridden from Histogram:
@@ -583,7 +580,6 @@ class BASE_EXPORT LinearHistogram : public Histogram {
   LinearHistogram(const std::string& name,
                   Sample minimum,
                   Sample maximum,
-                  size_t bucket_count,
                   const BucketRanges* ranges);
 
   virtual double GetBucketSize(Count current, size_t i) const OVERRIDE;