Make AudioParameters a class instead of a struct

content/common/media/audio_param_traits.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_COMMON_MEDIA_AUDIO_AUDIO_PARAM_TRAITS_H_
+#define CONTENT_COMMON_MEDIA_AUDIO_AUDIO_PARAM_TRAITS_H_
+#pragma once
+
+#include "ipc/ipc_message.h"
+#include "ipc/ipc_param_traits.h"
+
+class AudioParameters;
+
+namespace IPC {
+
+template <>
+struct ParamTraits<AudioParameters> {
+  typedef AudioParameters param_type;
+  static void Write(Message* m, const param_type& p);
+  static bool Read(const Message* m, PickleIterator* iter, param_type* r);
+  static void Log(const param_type& p, std::string* l);
+};
+
+} // namespace IPC
+
+#endif  // CONTENT_COMMON_MEDIA_AUDIO_AUDIO_PARAM_TRAITS_H_