Connect SparseHistogram with the rest of stats system

base/metrics/histogram_base_unittest.cc

 // Copyright (c) 2012 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.
 
 #include <vector>
 
 #include "base/metrics/histogram.h"
 #include "base/metrics/histogram_base.h"
 #include "base/metrics/sparse_histogram.h"
 #include "base/metrics/statistics_recorder.h"
@@ skipping 149 matching lines @@
 
   PickleIterator iter2(pickle);
   deserialized = DeserializeHistogramInfo(&iter2);
   EXPECT_TRUE(deserialized);
   EXPECT_NE(histogram, deserialized);
   EXPECT_EQ("TestHistogram", deserialized->histogram_name());
   EXPECT_TRUE(deserialized->HasConstructionArguments(5, 13, 4));
   EXPECT_EQ(0, deserialized->flags());
 }
 
-// TODO(kaiwang): Add SparseHistogram test.
+TEST_F(HistogramBaseTest, DeserializeSparseHistogram) {
+  HistogramBase* histogram = SparseHistogram::FactoryGet(
+      "TestHistogram", HistogramBase::kIPCSerializationSourceFlag);
+
+  Pickle pickle;
+  ASSERT_TRUE(histogram->SerializeInfo(&pickle));
+
+  PickleIterator iter(pickle);
+  HistogramBase* deserialized = DeserializeHistogramInfo(&iter);
+  EXPECT_EQ(histogram, deserialized);
+
+  ResetStatisticsRecorder();
+
+  PickleIterator iter2(pickle);
+  deserialized = DeserializeHistogramInfo(&iter2);
+  EXPECT_TRUE(deserialized);
+  EXPECT_NE(histogram, deserialized);
+  EXPECT_EQ("TestHistogram", deserialized->histogram_name());
+  EXPECT_EQ(0, deserialized->flags());
+}
 
 }  // namespace base