Add support to increase a UMA histogram bucket by an aribitrary integer.

base/metrics/histogram_base.h

Index: base/metrics/histogram_base.h
diff --git a/base/metrics/histogram_base.h b/base/metrics/histogram_base.h
index 1bc1f6eb6fe78bf4a48576f60e3da694a74da932..7f106877a1489462d377a3d705684f348cede60b 100644
--- a/base/metrics/histogram_base.h
+++ b/base/metrics/histogram_base.h
@@ -120,6 +120,10 @@ class BASE_EXPORT HistogramBase {
                                         size_t expected_bucket_count) const = 0;
 
   virtual void Add(Sample value) = 0;
+  // In Add function the |value| bucket is increased by one, but in some use

[Alexei Svitkine (slow), 2015/08/03 18:15:42]

Add a blank line before.

[amohammadkhan, 2015/08/04 18:22:51]

Done.

+  // cases we need to increase this value by an arbitrary integer. AddCount
+  // function increases the |value| bucket by |count|.
+  virtual void AddCount(Sample value, int count) = 0;
 
   // 2 convenient functions that call Add(Sample).
   void AddTime(const TimeDelta& time);