Add SampleMap and use it in SparseHistogram

base/metrics/sparse_histogram_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 <string>
 
 #include "base/memory/scoped_ptr.h"
+#include "base/metrics/sample_map.h"
 #include "base/metrics/sparse_histogram.h"
 #include "testing/gtest/include/gtest/gtest.h"
 
 namespace base {
 
 class SparseHistogramTest : public testing::Test {
  protected:
   scoped_ptr<SparseHistogram> NewSparseHistogram(const std::string& name) {
     return scoped_ptr<SparseHistogram>(new SparseHistogram(name));
   }
 };
 
 TEST_F(SparseHistogramTest, BasicTest) {
   scoped_ptr<SparseHistogram> histogram(NewSparseHistogram("Sparse1"));
-  std::map<HistogramBase::Sample, HistogramBase::Count> sample;
-  histogram->SnapshotSample(&sample);
-
-  ASSERT_EQ(0u, sample.size());
 
   histogram->Add(100);
-  histogram->SnapshotSample(&sample);
-  ASSERT_EQ(1u, sample.size());
-  EXPECT_EQ(1, sample[100]);
+  scoped_ptr<SampleMap> snapshot(histogram->SnapshotSamples());
+  EXPECT_EQ(1, snapshot->TotalCount());
+  EXPECT_EQ(1, snapshot->GetCount(100));
 
   histogram->Add(100);
   histogram->Add(101);
-  histogram->SnapshotSample(&sample);
-  ASSERT_EQ(2u, sample.size());
-  EXPECT_EQ(2, sample[100]);
-  EXPECT_EQ(1, sample[101]);
+  scoped_ptr<SampleMap> snapshot2(histogram->SnapshotSamples());
+  EXPECT_EQ(3, snapshot2->TotalCount());
+  EXPECT_EQ(2, snapshot2->GetCount(100));
+  EXPECT_EQ(1, snapshot2->GetCount(101));
 }
 
 }  // namespace base