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

base/metrics/sparse_histogram.cc

Index: base/metrics/sparse_histogram.cc
diff --git a/base/metrics/sparse_histogram.cc b/base/metrics/sparse_histogram.cc
index 21dd2ab7d97aecd12ca5a6a77083804ad1f75ec1..737ccad72f23553837ffebf47c2c4eaf59213ed5 100644
--- a/base/metrics/sparse_histogram.cc
+++ b/base/metrics/sparse_histogram.cc
@@ -39,9 +39,10 @@ HistogramType SparseHistogram::GetHistogramType() const {
   return SPARSE_HISTOGRAM;
 }
 
-bool SparseHistogram::HasConstructionArguments(Sample minimum,
-                                               Sample maximum,
-                                               size_t bucket_count) const {
+bool SparseHistogram::HasConstructionArguments(
+    Sample expected_minimum,
+    Sample expected_maximum,
+    size_t expected_bucket_count) const {
   // SparseHistogram never has min/max/bucket_count limit.
   return false;
 }