Return a NULL histogram pointer on construction error

base/metrics/histogram_unittest.cc

Index: base/metrics/histogram_unittest.cc
diff --git a/base/metrics/histogram_unittest.cc b/base/metrics/histogram_unittest.cc
index e7a01aa5af3d54bf1973f959822b1d989bd8417a..c6f0c8905ab3e399d1c2a51054ae79c4575e2b25 100644
--- a/base/metrics/histogram_unittest.cc
+++ b/base/metrics/histogram_unittest.cc
@@ -443,6 +443,54 @@ TEST_F(HistogramTest, CustomHistogramSerializeInfo) {
   EXPECT_FALSE(iter.SkipBytes(1));
 }
 
+TEST_F(HistogramTest, BadConstruction) {
+  HistogramBase* histogram = Histogram::FactoryGet(
+      "BadConstruction", 0, 100, 8,
+      HistogramBase::kNoFlags);
+  EXPECT_TRUE(
+      histogram->HasConstructionArguments(
+          1, 100, 8));
+  histogram->Add(10);
+
+  // Try to get the same histogram name with different arguments.
+  HistogramBase* dummy_histogram = Histogram::FactoryGet(
+      "BadConstruction", 0, 100, 7,
+      HistogramBase::kNoFlags);
+  dummy_histogram->Add(80);
+  dummy_histogram = Histogram::FactoryGet(
+      "BadConstruction", 0, 99, 8,
+      HistogramBase::kNoFlags);
+  dummy_histogram->Add(80);
+
+  scoped_ptr<HistogramSamples> samples = histogram->SnapshotSamples();
+  EXPECT_EQ(1, samples->TotalCount());
+  EXPECT_EQ(1, samples->GetCount(10));
+  EXPECT_EQ(0, samples->GetCount(80));
+
+  HistogramBase* linear_histogram = LinearHistogram::FactoryGet(
+      "BadConstructionLinear", 0, 100, 8,
+      HistogramBase::kNoFlags);
+  EXPECT_TRUE(
+      linear_histogram->HasConstructionArguments(
+          1, 100, 8));
+  linear_histogram->Add(10);
+
+  // Try to get the same histogram name with different arguments.
+  dummy_histogram = LinearHistogram::FactoryGet(
+      "BadConstructionLinear", 0, 100, 7,
+      HistogramBase::kNoFlags);
+  dummy_histogram->Add(80);
+  dummy_histogram = LinearHistogram::FactoryGet(
+      "BadConstructionLinear", 10, 100, 8,
+      HistogramBase::kNoFlags);
+  dummy_histogram->Add(80);
+
+  scoped_ptr<HistogramSamples> l_samples = linear_histogram->SnapshotSamples();
+  EXPECT_EQ(1, l_samples->TotalCount());
+  EXPECT_EQ(1, l_samples->GetCount(10));
+  EXPECT_EQ(0, l_samples->GetCount(80));
+}
+
 #if GTEST_HAS_DEATH_TEST
 // For Histogram, LinearHistogram and CustomHistogram, the minimum for a
 // declared range is 1, while the maximum is (HistogramBase::kSampleType_MAX -