CHECK -> DCHECK to prevent breaking exisitng histograms.

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 116 matching lines @@
   }
   DCHECK_EQ(count, redundant_count_);
   return count == redundant_count_;
 }
 
 Histogram* Histogram::FactoryGet(const string& name,
                                  Sample minimum,
                                  Sample maximum,
                                  size_t bucket_count,
                                  Flags flags) {
-  CHECK(InspectConstructionArguments(name, &minimum, &maximum, &bucket_count));
+  bool valid_arguments =
+      InspectConstructionArguments(name, &minimum, &maximum, &bucket_count);
+  DCHECK(valid_arguments);
 
   Histogram* histogram = StatisticsRecorder::FindHistogram(name);
   if (!histogram) {
     // To avoid racy destruction at shutdown, the following will be leaked.
     BucketRanges* ranges = new BucketRanges(bucket_count + 1);
     InitializeBucketRanges(minimum, maximum, bucket_count, ranges);
     const BucketRanges* registered_ranges =
         StatisticsRecorder::RegisterOrDeleteDuplicateRanges(ranges);
 
     Histogram* tentative_histogram =
@@ skipping 310 matching lines @@
                                              size_t* bucket_count) {
   // Defensive code for backward compatibility.
   if (*minimum < 1) {
     DVLOG(1) << "Histogram: " << name << " has bad minimum: " << *minimum;
     *minimum = 1;
   }
   if (*maximum >= kSampleType_MAX) {
     DVLOG(1) << "Histogram: " << name << " has bad maximum: " << *maximum;
     *maximum = kSampleType_MAX - 1;
   }
+  if (*bucket_count >= kBucketCount_MAX) {
+    DVLOG(1) << "Histogram: " << name << " has bad bucket_count: "
+             << *bucket_count;
+    *bucket_count = kBucketCount_MAX - 1;
+  }
 
-  if (*bucket_count < 3 || *bucket_count >= kBucketCount_MAX)
+  if (*minimum >= *maximum)
+    return false;
+  if (*bucket_count < 3)
     return false;
   if (*bucket_count > static_cast<size_t>(*maximum - *minimum + 2))
     return false;
   return true;
 }
 
 bool Histogram::SerializeRanges(Pickle* pickle) const {
   return true;
 }
 
@@ skipping 190 matching lines @@
 // buckets.
 //------------------------------------------------------------------------------
 
 LinearHistogram::~LinearHistogram() {}
 
 Histogram* LinearHistogram::FactoryGet(const string& name,
                                        Sample minimum,
                                        Sample maximum,
                                        size_t bucket_count,
                                        Flags flags) {
-  CHECK(Histogram::InspectConstructionArguments(name, &minimum, &maximum,
-                                                &bucket_count));
+  bool valid_arguments = Histogram::InspectConstructionArguments(
+      name, &minimum, &maximum, &bucket_count);
+  DCHECK(valid_arguments);
 
   Histogram* histogram = StatisticsRecorder::FindHistogram(name);
   if (!histogram) {
     // To avoid racy destruction at shutdown, the following will be leaked.
     BucketRanges* ranges = new BucketRanges(bucket_count + 1);
     InitializeBucketRanges(minimum, maximum, bucket_count, ranges);
     const BucketRanges* registered_ranges =
         StatisticsRecorder::RegisterOrDeleteDuplicateRanges(ranges);
 
     LinearHistogram* tentative_histogram =
@@ skipping 214 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