Create a histogram serialization mechanism in components/metrics

base/metrics/chromeos_metrics.h

+// 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_CHROMEOS_METRICS_H_
+#define BASE_METRICS_CHROMEOS_METRICS_H_
+
+#include "base/memory/scoped_vector.h"
+
+namespace base {
+class MetricSample;

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

What is the purpose of this file? Are these chromeos specific metrics functions?
If so, you probably want to cal them blahblah_chromeos.{cc|h}. This lets the
build tooling skip these files on non-CrOS builds.

[bsimonnet, 2014/04/14 23:03:05]

This will be used by chrome and libmetrics to communicate by reading and writing
from /var/log/metrics/uma-events. They will not be needed outside of chromeos so
we should suffix them.

+
+namespace ChromeOSMetrics {
+MetricSample* ReadSample(const std::string& sample);
+void ReadAndTruncateMetricsFromFile(const std::string& filename,
+                                    ScopedVector<MetricSample>* metrics);
+bool WriteMetricToFile(const MetricSample& sample, const std::string& filename);
+const int kMessageMaxLength = 1024;
+};

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

NIT: no ; Also needs // namespace ChromeOSMetrics.

+}  // namespace base
+#endif  // BASE_METRICS_CHROMEOS_METRICS_H_