Return a NULL histogram pointer on construction error

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 92 matching lines @@
 
     Histogram* tentative_histogram =
         new Histogram(name, minimum, maximum, registered_ranges);
 
     tentative_histogram->SetFlags(flags);
     histogram =
         StatisticsRecorder::RegisterOrDeleteDuplicate(tentative_histogram);
   }
 
   DCHECK_EQ(HISTOGRAM, histogram->GetHistogramType());
-  CHECK(histogram->HasConstructionArguments(minimum, maximum, bucket_count));
+  if (!histogram->HasConstructionArguments(minimum, maximum, bucket_count)) {
+    // The construction arguments do not match the existing histogram.  This can
+    // come about if an extension updates in the middle of a chrome run and has
+    // changed one of them.  We return a dummy object here instead of crashing
+    // so poor use of extension/Pepper APIs do not cause crashes in Chrome.
+    DLOG(ERROR) << "Histogram " << name << " has bad construction arguments";
+    DummyHistogram* tentative_histogram = new DummyHistogram;
+    histogram =
+        StatisticsRecorder::RegisterOrDeleteDuplicate(tentative_histogram);
+  }
   return histogram;
 }
 
 HistogramBase* Histogram::FactoryTimeGet(const string& name,
                                          TimeDelta minimum,
                                          TimeDelta maximum,
                                          size_t bucket_count,
                                          int32 flags) {
   return FactoryGet(name, minimum.InMilliseconds(), maximum.InMilliseconds(),
                     bucket_count, flags);
@@ skipping 436 matching lines @@
             descriptions[i].description;
       }
     }
 
     tentative_histogram->SetFlags(flags);
     histogram =
         StatisticsRecorder::RegisterOrDeleteDuplicate(tentative_histogram);
   }
 
   DCHECK_EQ(LINEAR_HISTOGRAM, histogram->GetHistogramType());
-  CHECK(histogram->HasConstructionArguments(minimum, maximum, bucket_count));
+  if (!histogram->HasConstructionArguments(minimum, maximum, bucket_count)) {
+    // The construction arguments do not match the existing histogram.  This can
+    // come about if an extension updates in the middle of a chrome run and has
+    // changed one of them.  We return a dummy object here instead of crashing
+    // so poor use of extension/Pepper APIs do not cause crashes in Chrome.
+    DLOG(ERROR) << "Histogram " << name << " has bad construction arguments";
+    DummyHistogram* tentative_histogram = new DummyHistogram;
+    histogram =
+        StatisticsRecorder::RegisterOrDeleteDuplicate(tentative_histogram);
+  }
   return histogram;
 }
 
 HistogramType LinearHistogram::GetHistogramType() const {
   return LINEAR_HISTOGRAM;
 }
 
 LinearHistogram::LinearHistogram(const string& name,
                                  Sample minimum,
                                  Sample maximum,
@@ skipping 243 matching lines @@
   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;
 }
 
+bool DummyHistogram::AddSamplesFromPickle(PickleIterator* iter) {
+  return false;
+}
+
+DummyHistogram::DummyHistogram() : Histogram("Dummy", 0, 1, NULL) {}
+
 }  // namespace base