Safeguard histogram accesses against null pointers....

base/histogram.h

 // Copyright (c) 2006-2008 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).
 
 // It supports calls to accumulate either time intervals (which are processed
 // as integral number of milliseconds), or arbitrary integral units.
@@ skipping 43 matching lines @@
 #define HISTOGRAM_COUNTS_100(name, sample) HISTOGRAM_CUSTOM_COUNTS( \
     name, sample, 1, 100, 50)
 
 #define HISTOGRAM_COUNTS_10000(name, sample) HISTOGRAM_CUSTOM_COUNTS( \
     name, sample, 1, 10000, 50)
 
 #define HISTOGRAM_CUSTOM_COUNTS(name, sample, min, max, bucket_count) do { \
     static scoped_refptr<Histogram> counter = Histogram::FactoryGet( \
         name, min, max, bucket_count, Histogram::kNoFlags); \
     DCHECK_EQ(name, counter->histogram_name()); \
-    counter->Add(sample); \
+    if (counter.get()) counter->Add(sample); \
   } while (0)
 
 #define HISTOGRAM_PERCENTAGE(name, under_one_hundred) \
     HISTOGRAM_ENUMERATION(name, under_one_hundred, 101)
 
 // For folks that need real specific times, use this to select a precise range
 // of times you want plotted, and the number of buckets you want used.
 #define HISTOGRAM_CUSTOM_TIMES(name, sample, min, max, bucket_count) do { \
     static scoped_refptr<Histogram> counter = Histogram::FactoryTimeGet( \
         name, min, max, bucket_count, Histogram::kNoFlags); \
     DCHECK_EQ(name, counter->histogram_name()); \
-    counter->AddTime(sample); \
+    if (counter.get()) counter->AddTime(sample); \
   } while (0)
 
 // DO NOT USE THIS.  It is being phased out, in favor of HISTOGRAM_CUSTOM_TIMES.
 #define HISTOGRAM_CLIPPED_TIMES(name, sample, min, max, bucket_count) do { \
     static scoped_refptr<Histogram> counter = Histogram::FactoryTimeGet( \
         name, min, max, bucket_count, Histogram::kNoFlags); \
     DCHECK_EQ(name, counter->histogram_name()); \
-    if ((sample) < (max)) counter->AddTime(sample); \
+    if ((sample) < (max) && counter.get()) counter->AddTime(sample); \
   } while (0)
 
 // Support histograming of an enumerated value.  The samples should always be
 // less than boundary_value.
 
 #define HISTOGRAM_ENUMERATION(name, sample, boundary_value) do { \
     static scoped_refptr<Histogram> counter = LinearHistogram::FactoryGet( \
         name, 1, boundary_value, boundary_value + 1, Histogram::kNoFlags); \
     DCHECK_EQ(name, counter->histogram_name()); \
-    counter->Add(sample); \
+    if (counter.get()) counter->Add(sample); \
   } while (0)
 
 #define HISTOGRAM_CUSTOM_ENUMERATION(name, sample, custom_ranges) do { \
     static scoped_refptr<Histogram> counter = CustomHistogram::FactoryGet( \
         name, custom_ranges, Histogram::kNoFlags); \
     DCHECK_EQ(name, counter->histogram_name()); \
-    counter->Add(sample); \
+    if (counter.get()) counter->Add(sample); \
   } while (0)
 
 
 //------------------------------------------------------------------------------
 // Define Debug vs non-debug flavors of macros.
 #ifndef NDEBUG
 
 #define DHISTOGRAM_TIMES(name, sample) HISTOGRAM_TIMES(name, sample)
 #define DHISTOGRAM_COUNTS(name, sample) HISTOGRAM_COUNTS(name, sample)
 #define DHISTOGRAM_PERCENTAGE(name, under_one_hundred) HISTOGRAM_PERCENTAGE(\
@@ skipping 42 matching lines @@
 
 // Use this macro when times can routinely be much longer than 10 seconds.
 #define UMA_HISTOGRAM_LONG_TIMES(name, sample) UMA_HISTOGRAM_CUSTOM_TIMES( \
     name, sample, base::TimeDelta::FromMilliseconds(1), \
     base::TimeDelta::FromHours(1), 50)
 
 #define UMA_HISTOGRAM_CUSTOM_TIMES(name, sample, min, max, bucket_count) do { \
     static scoped_refptr<Histogram> counter = Histogram::FactoryTimeGet( \
         name, min, max, bucket_count, Histogram::kUmaTargetedHistogramFlag); \
     DCHECK_EQ(name, counter->histogram_name()); \
-    counter->AddTime(sample); \
+    if (counter.get()) counter->AddTime(sample); \
   } while (0)
 
 // DO NOT USE THIS.  It is being phased out, in favor of HISTOGRAM_CUSTOM_TIMES.
 #define UMA_HISTOGRAM_CLIPPED_TIMES(name, sample, min, max, bucket_count) do { \
     static scoped_refptr<Histogram> counter = Histogram::FactoryTimeGet( \
         name, min, max, bucket_count, Histogram::kUmaTargetedHistogramFlag); \
     DCHECK_EQ(name, counter->histogram_name()); \
-    if ((sample) < (max)) counter->AddTime(sample); \
+    if ((sample) < (max) && counter.get()) counter->AddTime(sample); \
   } while (0)
 
 #define UMA_HISTOGRAM_COUNTS(name, sample) UMA_HISTOGRAM_CUSTOM_COUNTS( \
     name, sample, 1, 1000000, 50)
 
 #define UMA_HISTOGRAM_COUNTS_100(name, sample) UMA_HISTOGRAM_CUSTOM_COUNTS( \
     name, sample, 1, 100, 50)
 
 #define UMA_HISTOGRAM_COUNTS_10000(name, sample) UMA_HISTOGRAM_CUSTOM_COUNTS( \
     name, sample, 1, 10000, 50)
 
 #define UMA_HISTOGRAM_CUSTOM_COUNTS(name, sample, min, max, bucket_count) do { \
     static scoped_refptr<Histogram> counter = Histogram::FactoryGet( \
         name, min, max, bucket_count, Histogram::kUmaTargetedHistogramFlag); \
     DCHECK_EQ(name, counter->histogram_name()); \
-    counter->Add(sample); \
+    if (counter.get()) counter->Add(sample); \
   } while (0)
 
 #define UMA_HISTOGRAM_MEMORY_KB(name, sample) UMA_HISTOGRAM_CUSTOM_COUNTS( \
     name, sample, 1000, 500000, 50)
 
 #define UMA_HISTOGRAM_MEMORY_MB(name, sample) UMA_HISTOGRAM_CUSTOM_COUNTS( \
     name, sample, 1, 1000, 50)
 
 #define UMA_HISTOGRAM_PERCENTAGE(name, under_one_hundred) \
     UMA_HISTOGRAM_ENUMERATION(name, under_one_hundred, 101)
 
 #define UMA_HISTOGRAM_ENUMERATION(name, sample, boundary_value) do { \
     static scoped_refptr<Histogram> counter = LinearHistogram::FactoryGet( \
         name, 1, boundary_value, boundary_value + 1, \
         Histogram::kUmaTargetedHistogramFlag); \
     DCHECK_EQ(name, counter->histogram_name()); \
-    counter->Add(sample); \
+    if (counter.get()) counter->Add(sample); \
   } while (0)
 
 #define UMA_HISTOGRAM_CUSTOM_ENUMERATION(name, sample, custom_ranges) do { \
     static scoped_refptr<Histogram> counter = CustomHistogram::FactoryGet( \
         name, custom_ranges, Histogram::kUmaTargetedHistogramFlag); \
     DCHECK_EQ(name, counter->histogram_name()); \
-    counter->Add(sample); \
+    if (counter.get()) counter->Add(sample); \
   } while (0)
 
 //------------------------------------------------------------------------------
 
 class BooleanHistogram;
 class CustomHistogram;
 class Histogram;
 class LinearHistogram;
 class Pickle;
 
@@ skipping 404 matching lines @@
   // lock protects access to the above map.
   static Lock* lock_;
 
   // Dump all known histograms to log.
   static bool dump_on_exit_;
 
   DISALLOW_COPY_AND_ASSIGN(StatisticsRecorder);
 };
 
 #endif  // BASE_HISTOGRAM_H_