Create a histogram serialization mechanism in components/metrics

components/metrics/export/sparsehistogram_sample.cc

Index: components/metrics/export/sparsehistogram_sample.cc
diff --git a/components/metrics/export/sparsehistogram_sample.cc b/components/metrics/export/sparsehistogram_sample.cc
new file mode 100644
index 0000000000000000000000000000000000000000..d674653253817cf45c15066f2f4e56e3319d2ef8
--- /dev/null
+++ b/components/metrics/export/sparsehistogram_sample.cc
@@ -0,0 +1,47 @@
+// Copyright 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.
+
+#include "components/metrics/export/sparsehistogram_sample.h"
+
+#include <string>
+#include <vector>
+
+#include "base/memory/scoped_ptr.h"
+#include "base/strings/string_number_conversions.h"
+#include "base/strings/string_split.h"
+#include "base/strings/stringprintf.h"
+#include "components/metrics/export/metric_sample.h"
+
+namespace metrics {
+
+SparseHistogramSample::SparseHistogramSample(const std::string& histogram_name,
+                                             int sample)
+    : MetricSample(MetricSample::SPARSE_HISTOGRAM, histogram_name),
+      sample_(sample) {}
+
+SparseHistogramSample::~SparseHistogramSample() {}
+
+std::string SparseHistogramSample::ToString() const {
+  return base::StringPrintf(
+      "sparsehistogram%c%s %d%c", '\0', name().c_str(), sample_, '\0');
+}
+
+// static
+// Read a sparse histogram from a string listing |name| and |sample| separated
+// by a space.
+scoped_ptr<SparseHistogramSample> SparseHistogramSample::ReadSparseHistogram(
+    const std::string& histogram_serialized) {

[Alexei Svitkine (slow), 2014/05/01 15:57:09]

Nit: serialized_histogram which also makes it consistent with .h file.

+  std::vector<std::string> parts;
+  base::SplitString(histogram_serialized, ' ', &parts);
+  if (parts.size() != 2)
+    return scoped_ptr<SparseHistogramSample>();
+  int sample;
+  if (parts[0].length() == 0 || !base::StringToInt(parts[1], &sample))
+    return scoped_ptr<SparseHistogramSample>();
+
+  return scoped_ptr<SparseHistogramSample>(
+      new SparseHistogramSample(parts[0], sample));
+}
+
+}  // namespace metrics