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

base/metrics/sparse_histogram.h

Index: base/metrics/sparse_histogram.h
diff --git a/base/metrics/sparse_histogram.h b/base/metrics/sparse_histogram.h
index 870b06b567101179c943e66402cbf047bceb3743..07d56603a5d8b4b7a85caadedbbf67d6dba39215 100644
--- a/base/metrics/sparse_histogram.h
+++ b/base/metrics/sparse_histogram.h
@@ -64,9 +64,10 @@ class BASE_EXPORT_PRIVATE SparseHistogram : 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 void AddSamples(const HistogramSamples& samples) OVERRIDE;
   virtual bool AddSamplesFromPickle(PickleIterator* iter) OVERRIDE;