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

base/metrics/histogram.cc

 // Copyright (c) 2012 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 // Histogram is an object that aggregates statistics, and can summarize them in
 // various forms, including ASCII graphical, HTML, and numerically (as a
 // vector of numbers corresponding to each of the aggregating buckets).
 // See header file for details and examples.
 
 #include "base/metrics/histogram.h"
@@ skipping 266 matching lines @@
 
   if (value > kSampleType_MAX - 1)
     value = kSampleType_MAX - 1;
   if (value < 0)
     value = 0;
   samples_->Accumulate(value, 1);
 
   FindAndRunCallback(value);
 }
 
+void Histogram::MultiAdd(int value, int count) {

[Alexei Svitkine (slow), 2015/07/31 15:39:27]

We should disallow negative values.

[amohammadkhan, 2015/08/03 17:30:43]

Done. I change negative values to zero. Is it good enough or I have to make an
assertion or something else?

+  DCHECK_EQ(0, ranges(0));
+  DCHECK_EQ(kSampleType_MAX, ranges(bucket_count()));
+
+  if (value > kSampleType_MAX - 1)
+    value = kSampleType_MAX - 1;
+  if (value < 0)
+    value = 0;

[Alexei Svitkine (slow), 2015/07/31 15:39:27]

Can you make a helper function for this clamping in the anon namespace and use
it both here and in Add().

[amohammadkhan, 2015/08/03 17:30:43]

Done.

+  samples_->Accumulate(value, count);
+
+  FindAndRunCallback(value);
+

[Alexei Svitkine (slow), 2015/07/31 15:39:27]

Nit: Remove empty line.

[amohammadkhan, 2015/08/03 17:30:43]

Done.

+}
+
 scoped_ptr<HistogramSamples> Histogram::SnapshotSamples() const {
   return SnapshotSampleVector().Pass();
 }
 
 void Histogram::AddSamples(const HistogramSamples& samples) {
   samples_->Add(samples);
 }
 
 bool Histogram::AddSamplesFromPickle(PickleIterator* iter) {
   return samples_->AddFromPickle(iter);
@@ skipping 587 matching lines @@
 
   BucketRanges* bucket_ranges = new BucketRanges(ranges.size());
   for (size_t i = 0; i < ranges.size(); i++) {
     bucket_ranges->set_range(i, ranges[i]);
   }
   bucket_ranges->ResetChecksum();
   return bucket_ranges;
 }
 
 }  // namespace base