Create a histogram serialization mechanism in components/metrics

components/metrics/export/useraction_sample.cc

Index: components/metrics/export/useraction_sample.cc
diff --git a/components/metrics/export/useraction_sample.cc b/components/metrics/export/useraction_sample.cc
new file mode 100644
index 0000000000000000000000000000000000000000..4723924de5de905ca80dc7f2a1e26d042e7165da
--- /dev/null
+++ b/components/metrics/export/useraction_sample.cc
@@ -0,0 +1,31 @@
+// 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/useraction_sample.h"
+
+#include <string>
+
+#include "base/strings/stringprintf.h"
+#include "components/metrics/export/metric_sample.h"
+
+using base::StringPrintf;
+using std::string;
+
+namespace metrics {
+
+UserActionSample::UserActionSample(const std::string& action_name)
+    : MetricSample(MetricSample::USER_ACTION, action_name) {}
+
+UserActionSample::~UserActionSample() {}
+
+string UserActionSample::ToString() const {
+  return StringPrintf("useraction%c%s%c", '\0', name().c_str(), '\0');
+}
+
+// static
+UserActionSample* UserActionSample::ReadUserAction(const std::string& action) {
+  return new UserActionSample(action);

[Alexei Svitkine (slow), 2014/04/30 15:25:24]

I believe the best practice for APIs that transfer ownership of the object
returned is to return the object as a scoped_ptr<Type>. Can you change to this
style throughout?

[bsimonnet, 2014/04/30 20:28:40]

Done.

[bsimonnet, 2014/04/30 20:28:40]

Yes, it is probably much cleaner.

+}
+
+}  // namespace metrics