Create a histogram serialization mechanism in components/metrics

base/metrics/sparsehistogram_sample.h

Index: base/metrics/sparsehistogram_sample.h
diff --git a/base/metrics/sparsehistogram_sample.h b/base/metrics/sparsehistogram_sample.h
new file mode 100644
index 0000000000000000000000000000000000000000..741ca66b93283e8bdf72fb6ccd7434443ca99fd3
--- /dev/null
+++ b/base/metrics/sparsehistogram_sample.h
@@ -0,0 +1,28 @@
+// Copyright (c) 2014 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.
+
+#ifndef BASE_METRICS_SPARSEHISTOGRAM_SAMPLE_H
+#define BASE_METRICS_SPARSEHISTOGRAM_SAMPLE_H
+
+#include <string>
+
+#include "base/base_export.h"
+#include "base/metrics/metric_sample.h"
+
+namespace base {
+class BASE_EXPORT SparseHistogramSample : public MetricSample {
+ public:
+  SparseHistogramSample(const std::string& histname, int sample);
+  virtual ~SparseHistogramSample();
+  int sample();

[gauravsh, 2014/04/11 23:50:51]

this can be a const function.

+  // static
+  static SparseHistogramSample* ReadSparseHistogram(

[gauravsh, 2014/04/11 23:50:51]

Needs comment.

+      const std::string& serializedhist);

[gauravsh, 2014/04/11 23:50:51]

NIT: serialized_hist. Also avoid abbreviations wherever possible. so perhaps
serialized_histograms

+  string toString() const;
+
+ protected:
+  int sample_;

[gauravsh, 2014/04/11 23:50:51]

Do you intend to subclass this? make this private. If you want tests to access
use FRIEND_TEST or friend class.

+};
+}  // namespace base
+#endif  // BASE_METRICS_SPARSEHISTOGRAM_SAMPLE_H