1. Add test for https://src.chromium.org/viewvc/chrome?view=rev&revision=149541

base/metrics/histogram_unittest.cc

Index: base/metrics/histogram_unittest.cc
===================================================================
--- base/metrics/histogram_unittest.cc	(revision 149495)
+++ base/metrics/histogram_unittest.cc	(working copy)
@@ -319,4 +319,53 @@
   bucket_ranges->set_range(4, bucket_ranges->range(4) + 1);
 }
 
+#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 -
+// 1). But we accept ranges exceeding those limits, and silently clamped to
+// those limits. This is for backwards compatibility.
+TEST(HistogramDeathTest, BadRangesTest) {
+  Histogram* histogram =
+      Histogram::FactoryGet("BadRanges", 0, HistogramBase::kSampleType_MAX, 8,
+                            Histogram::kNoFlags);

[jar (doing other things), 2012/08/03 21:53:42]

nit: consider wrapping on only two lines.

[kaiwang, 2012/08/03 22:15:53]

Done.

+  EXPECT_EQ(1, histogram->declared_min());
+  EXPECT_EQ(HistogramBase::kSampleType_MAX - 1, histogram->declared_max());
+
+  Histogram* linear_histogram =
+      LinearHistogram::FactoryGet("BadRangesLinear", 0,
+                                  HistogramBase::kSampleType_MAX, 8,
+                                  Histogram::kNoFlags);
+  EXPECT_EQ(1, linear_histogram->declared_min());
+  EXPECT_EQ(HistogramBase::kSampleType_MAX - 1,
+            linear_histogram->declared_max());
+
+  vector<int> custom_ranges;
+  custom_ranges.push_back(0);
+  custom_ranges.push_back(5);
+  Histogram* custom_histogram1 =
+      CustomHistogram::FactoryGet("BadRangesCustom", custom_ranges,
+                                  Histogram::kNoFlags);
+  const BucketRanges* ranges = custom_histogram1->bucket_ranges();
+  ASSERT_EQ(3u, ranges->size());
+  EXPECT_EQ(0, ranges->range(0));
+  EXPECT_EQ(5, ranges->range(1));
+  EXPECT_EQ(HistogramBase::kSampleType_MAX, ranges->range(2));
+
+  // CustomHistogram does not accepts kSampleType_MAX as range.
+  custom_ranges.push_back(HistogramBase::kSampleType_MAX);
+  EXPECT_DEATH(
+      CustomHistogram::FactoryGet("BadRangesCustom2", custom_ranges,
+                                  Histogram::kNoFlags),
+      "");
+
+  // CustomHistogram needs at least 1 valid range.
+  custom_ranges.clear();
+  custom_ranges.push_back(0);
+  EXPECT_DEATH(
+      CustomHistogram::FactoryGet("BadRangesCustom3", custom_ranges,
+                                  Histogram::kNoFlags),
+      "");

[jar (doing other things), 2012/08/03 21:53:42]

nit: Suggest:
 EXPECT_DEATH(CustomHistogram::FactoryGet("BadRangesCustom2", custom_ranges,
                                          Histogram::kNoFlags),
              "");

[kaiwang, 2012/08/03 22:15:53]

Done.

+}
+#endif
+
 }  // namespace base