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

base/metrics/histogram.cc

Index: base/metrics/histogram.cc
diff --git a/base/metrics/histogram.cc b/base/metrics/histogram.cc
index 7ff1b16184f10c9e54dd501b1b95a1f34fefc253..b37bc4c4685c5476c9145a81bb953ddfbc2532d5 100644
--- a/base/metrics/histogram.cc
+++ b/base/metrics/histogram.cc
@@ -272,6 +272,10 @@ bool Histogram::HasConstructionArguments(Sample expected_minimum,
 }
 
 void Histogram::Add(int value) {
+  AddCount(value, 1);
+}
+
+void Histogram::AddCount(int value, int count) {
   DCHECK_EQ(0, ranges(0));
   DCHECK_EQ(kSampleType_MAX, ranges(bucket_count()));
 
@@ -279,7 +283,11 @@ void Histogram::Add(int value) {
     value = kSampleType_MAX - 1;
   if (value < 0)
     value = 0;
-  samples_->Accumulate(value, 1);
+  if (count <= 0) {
+    NOTREACHED();
+    return;
+  }
+  samples_->Accumulate(value, count);
 
   FindAndRunCallback(value);
 }