Create a histogram serialization mechanism in components/metrics

base/metrics/useraction_sample.cc

+// 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/useraction_sample.h"
+
+#include <string>
+
+#include "base/metrics/chromeos_metrics.h"
+#include "base/metrics/metric_sample.h"
+
+using std::string;
+
+namespace base {
+
+UserActionSample::UserActionSample(const std::string& _action):
+  MetricSample(MetricSample::USER_ACTION) {
+  action = _action;
+}
+std::string UserActionSample::getAction() {
+  return action;
+}
+
+UserActionSample* UserActionSample::ReadUserAction(const std::string& action) {
+  return new UserActionSample(action);
+}
+
+UserActionSample::~UserActionSample() {}
+
+int UserActionSample::Write(int buffer_size, char* buffer) {
+  return ChromeOSMetrics::FormatSample(buffer_size, buffer,
+                              "useraction%c%s", '\0', action.c_str());
+}
+}  // namespace base