Create a histogram serialization mechanism in components/metrics

base/metrics/sparsehistogram_sample_chromeos.cc

Index: base/metrics/sparsehistogram_sample_chromeos.cc
diff --git a/base/metrics/sparsehistogram_sample_chromeos.cc b/base/metrics/sparsehistogram_sample_chromeos.cc
new file mode 100644
index 0000000000000000000000000000000000000000..c2cbc928bbc319e2e0f87420966e3ede22fad71c
--- /dev/null
+++ b/base/metrics/sparsehistogram_sample_chromeos.cc
@@ -0,0 +1,46 @@
+// 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.
+
+#include "base/metrics/sparsehistogram_sample_chromeos.h"
+
+#include <string>
+
+#include "base/metrics/metric_sample_chromeos.h"
+#include "base/strings/string_number_conversions.h"
+#include "base/strings/string_split.h"
+#include "base/strings/stringprintf.h"
+
+using std::string;
+using std::vector;
+
+namespace base {
+
+SparseHistogramSample::SparseHistogramSample(const std::string& histogram_name,
+                                             int sample)
+    : MetricSample(MetricSample::SPARSE_HISTOGRAM, histogram_name),
+      sample_(sample) {}
+
+int SparseHistogramSample::sample() const { return sample_; }
+
+SparseHistogramSample* SparseHistogramSample::ReadSparseHistogram(
+    const std::string& histogram_serialized) {
+  vector<string> parts;
+  SplitString(histogram_serialized, ' ', &parts);
+  if (parts.size() != 2) {

[Alexei Svitkine (slow), 2014/04/17 16:33:21]

Nit: No need for {}'s for single-line bodies. Please fix throughout.

+    return NULL;
+  }
+  int sample;
+  if (!StringToInt(parts[1], &sample)) {
+    return NULL;
+  }
+  return new SparseHistogramSample(parts[0], sample);
+}
+
+SparseHistogramSample::~SparseHistogramSample() {}
+
+string SparseHistogramSample::ToString() const {
+  return StringPrintf(
+      "sparsehistogram%c%s %d%c", '\0', name_.c_str(), sample_, '\0');
+}
+}  // namespace base