1. Add test for https://src.chromium.org/viewvc/chrome?view=rev&revision=149541

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 865 matching lines @@
   return true;
 }
 
 double CustomHistogram::GetBucketSize(Count current, size_t i) const {
   return 1;
 }
 
 // static
 bool CustomHistogram::ValidateCustomRanges(
     const vector<Sample>& custom_ranges) {
-  if (custom_ranges.size() < 1)
-    return false;
+  int valid_ranges = 0;

[jar (doing other things), 2012/08/03 21:53:42]

Suggest use boolean:
bool valid_ranges = false;

then set where you would increment.

[kaiwang, 2012/08/03 22:15:53]

Done.

   for (size_t i = 0; i < custom_ranges.size(); i++) {
     Sample s = custom_ranges[i];

[jar (doing other things), 2012/08/03 21:53:42]

nit: (on existing code): Please use |sample| instead of s

[kaiwang, 2012/08/03 22:15:53]

Done.

     if (s < 0 || s > HistogramBase::kSampleType_MAX - 1)
       return false;
+    if (s != 0)
+      valid_ranges++;
   }
-  return true;
+  return valid_ranges > 0;
 }
 
 // static
 BucketRanges* CustomHistogram::CreateBucketRangesFromCustomRanges(
       const vector<Sample>& custom_ranges) {
   // Remove the duplicates in the custom ranges array.
   vector<int> ranges = custom_ranges;
   ranges.push_back(0);  // Ensure we have a zero value.
   ranges.push_back(HistogramBase::kSampleType_MAX);
   std::sort(ranges.begin(), ranges.end());
   ranges.erase(std::unique(ranges.begin(), ranges.end()), ranges.end());
 
   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