Return a NULL histogram pointer on construction error

chrome/browser/extensions/api/metrics_private/metrics_private_api.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.
 
 #include "chrome/browser/extensions/api/metrics_private/metrics_private_api.h"
 
 #include <algorithm>
 
 #include "base/metrics/field_trial.h"
 #include "base/metrics/histogram.h"
@@ skipping 121 matching lines @@
   if (type == base::LINEAR_HISTOGRAM) {
     counter = base::LinearHistogram::FactoryGet(
         name, min, max, buckets,
         base::HistogramBase::kUmaTargetedHistogramFlag);
   } else {
     counter = base::Histogram::FactoryGet(
         name, min, max, buckets,
         base::HistogramBase::kUmaTargetedHistogramFlag);
   }
 
-  counter->Add(sample);
+  // The histogram can be NULL if it is constructed with bad arguments.  Ignore
+  // that data for this API.  An error message will be logged.
+  if (counter)
+    counter->Add(sample);
   return true;
 }
 
 bool MetricsPrivateRecordValueFunction::RunImpl() {
   scoped_ptr<RecordValue::Params> params(RecordValue::Params::Create(*args_));
   EXTENSION_FUNCTION_VALIDATE(params.get());
 
   // Get the histogram parameters from the metric type object.
   std::string type = api::metrics_private::MetricType::ToString(
       params->metric.type);
@@ skipping 56 matching lines @@
 bool MetricsPrivateRecordLongTimeFunction::RunImpl() {
   scoped_ptr<RecordLongTime::Params> params(
       RecordLongTime::Params::Create(*args_));
   EXTENSION_FUNCTION_VALIDATE(params.get());
   static const int kOneHourMs = 60 * 60 * 1000;
   return RecordValue(params->metric_name, base::HISTOGRAM,
                      1, kOneHourMs, 50, params->value);
 }
 
 } // namespace extensions