[UMA] Use proper C++ objects to serialize tracked_objects across process boundaries.

content/public/common/serialized_profiler_data.h

+// Copyright (c) 2012 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 CONTENT_PUBLIC_COMMON_SERIALIZED_PROFILER_DATA_H
+#define CONTENT_PUBLIC_COMMON_SERIALIZED_PROFILER_DATA_H
+#pragma once
+
+#include <string>
+#include <vector>
+
+#include "base/tracked_objects.h"
+#include "content/common/content_export.h"
+#include "content/public/common/process_type.h"
+
+namespace base {
+class DictionaryValue;
+}
+
+namespace content {
+
+// Extends SerializedProcessData with the process's type info.
+struct CONTENT_EXPORT SerializedProfilerData :
+    public tracked_objects::SerializedProcessData {

[jam, 2012/03/14 17:45:31]

in content/public we put interfaces and dont derived from concrete types. it's
similar to WebKit API
see http://www.chromium.org/developers/content-module/content-api

[Ilya Sherman, 2012/03/14 18:01:28]

This is currently a struct, which is just a dumb data container used for IPC
serialization.  (There is also a trivial ToValue() method, to re-serialize to
JSON.  That doesn't really have to live in content/, though it is consistent
with how the similar dumb data containers are defined in base/.)  The link you
pointed me at seems to include an exception for structs: "it's acceptable to put
implementation files that hold constructors/destructors of interfaces/structs
which might have member variables. For structs..."

If that exception is not relevant to this class, could you please explain why
not, and perhaps update the API docs?  Also, if that exception is not relevant,
what would you recommend -- reworking this struct to be a proper class, with
private member variables and public accessors?  That seems unduly tedious just
to provide a handy container for serialization...

[Ilya Sherman, 2012/03/16 22:56:42]

Ok, removed this struct entirely in favor of passing two separate parameters.

+  SerializedProfilerData();
+  SerializedProfilerData(content::ProcessType process_type);
+  ~SerializedProfilerData();
+
+  void ToValue(base::DictionaryValue* dictionary) const;

[jam, 2012/03/14 19:14:03]

one more note: this is against the style guide for a struct

[Ilya Sherman, 2012/03/16 22:56:42]

Very well, extracted this out to a static function in chrome/browser instead.

+
+  content::ProcessType process_type;
+};
+
+}  // namespace content
+
+#endif  // CONTENT_PUBLIC_COMMON_SERIALIZED_PROFILER_DATA_H