Add Sparse Histogram Support to metricsPrivate

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 f910a35279edd9860388eae837e309b56e313b30..8f7ec4b4bb715348af69e3d4068e61f423ea496f 100644
--- a/chrome/browser/extensions/api/metrics_private/metrics_apitest.cc
+++ b/chrome/browser/extensions/api/metrics_private/metrics_apitest.cc
@@ -38,6 +38,8 @@ struct RecordedHistogram {
       {"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.sparse.1", base::SPARSE_HISTOGRAM, 0, 0, 0, 1},
+      {"test.sparse.2", base::SPARSE_HISTOGRAM, 0, 0, 0, 2},
       {"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},
@@ -116,8 +118,13 @@ void ValidateHistograms(const RecordedHistogram* recorded,
 
       if (r.name == histogram->histogram_name()) {
         EXPECT_EQ(r.type, histogram->GetHistogramType());
-        EXPECT_TRUE(
-            histogram->HasConstructionArguments(r.min, r.max, r.buckets));
+        if (r.type == base::SPARSE_HISTOGRAM) {
+          EXPECT_FALSE(
+              histogram->HasConstructionArguments(r.min, r.max, r.buckets));
+        } else {
+          EXPECT_TRUE(
+              histogram->HasConstructionArguments(r.min, r.max, r.buckets));
+        }
         scoped_ptr<base::HistogramSamples> snapshot =
             histogram->SnapshotSamples();
         base::HistogramBase::Count sample_count = snapshot->TotalCount();