Return a NULL histogram pointer on construction error

chrome/browser/extensions/api/metrics_private/metrics_apitest.cc

Index: chrome/browser/extensions/api/metrics_private/metrics_apitest.cc
diff --git a/chrome/browser/extensions/api/metrics_private/metrics_apitest.cc b/chrome/browser/extensions/api/metrics_private/metrics_apitest.cc
index 86eb577a59196b81c93154eaf89706accf07d150..f6ae17112256cded895f22d2b5a50df9b5b33a04 100644
--- a/chrome/browser/extensions/api/metrics_private/metrics_apitest.cc
+++ b/chrome/browser/extensions/api/metrics_private/metrics_apitest.cc
@@ -33,16 +33,19 @@ struct RecordedHistogram {
   int min;
   int max;
   size_t buckets;
+  int count;
 } g_histograms[] = {
-  {"test.h.1", base::HISTOGRAM, 1, 100, 50},  // custom
-  {"test.h.2", base::LINEAR_HISTOGRAM, 1, 200, 50},  // custom
-  {"test.h.3", base::LINEAR_HISTOGRAM, 1, 101, 102},  // percentage
-  {"test.time", base::HISTOGRAM, 1, 10000, 50},
-  {"test.medium.time", base::HISTOGRAM, 1, 180000, 50},
-  {"test.long.time", base::HISTOGRAM, 1, 3600000, 50},
-  {"test.count", base::HISTOGRAM, 1, 1000000, 50},
-  {"test.medium.count", base::HISTOGRAM, 1, 10000, 50},
-  {"test.small.count", base::HISTOGRAM, 1, 100, 50},
+  {"test.h.1", base::HISTOGRAM, 1, 100, 50, 1},  // custom
+  {"test.h.2", base::LINEAR_HISTOGRAM, 1, 200, 50, 1},  // custom
+  {"test.h.3", base::LINEAR_HISTOGRAM, 1, 101, 102, 2},  // percentage
+  {"test.time", base::HISTOGRAM, 1, 10000, 50, 1},
+  {"test.medium.time", base::HISTOGRAM, 1, 180000, 50, 1},
+  {"test.long.time", base::HISTOGRAM, 1, 3600000, 50, 1},
+  {"test.count", base::HISTOGRAM, 1, 1000000, 50, 1},
+  {"test.medium.count", base::HISTOGRAM, 1, 10000, 50, 1},
+  {"test.small.count", base::HISTOGRAM, 1, 100, 50, 1},
+  {"test.bucketchange.linear", base::LINEAR_HISTOGRAM, 1, 100, 10, 2},

[Alexei Svitkine (slow), 2014/01/17 15:40:13]

Can you also add tests for this to histogram_unittest.cc?

[elijahtaylor1, 2014/01/17 20:04:16]

Done.

+  {"test.bucketchange.log", base::HISTOGRAM, 1, 100, 10, 2},
 };
 
 // This class observes and collects user action notifications that are sent
@@ -116,6 +119,10 @@ void ValidateHistograms(const RecordedHistogram* recorded,
         EXPECT_EQ(r.type, histogram->GetHistogramType());
         EXPECT_TRUE(
             histogram->HasConstructionArguments(r.min, r.max, r.buckets));
+        scoped_ptr<base::HistogramSamples> snapshot =
+            histogram->SnapshotSamples();
+        base::HistogramBase::Count sample_count = snapshot->TotalCount();
+        EXPECT_EQ(sample_count, r.count);
         break;
       }
     }