Refactor the TrayAudio code so that it can be used by other platforms.

ash/system/chromeos/audio/tray_audio_chromeos.cc

Index: ash/system/chromeos/audio/tray_audio_chromeos.cc
diff --git a/ash/system/chromeos/audio/tray_audio_chromeos.cc b/ash/system/chromeos/audio/tray_audio_chromeos.cc
new file mode 100644
index 0000000000000000000000000000000000000000..d0531fdc97891620301eed27e40907dd144a8a7c
--- /dev/null
+++ b/ash/system/chromeos/audio/tray_audio_chromeos.cc
@@ -0,0 +1,57 @@
+// 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.
+
+#include "ash/system/chromeos/audio/tray_audio_chromeos.h"
+
+#include "ash/ash_switches.h"
+#include "ash/metrics/user_metrics_recorder.h"
+#include "ash/shell.h"
+#include "ash/system/audio/volume_view.h"
+#include "ash/system/chromeos/audio/audio_detailed_view.h"
+#include "ui/views/view.h"
+
+namespace ash {
+namespace internal {
+
+TrayAudioChromeOs::TrayAudioChromeOs(
+    SystemTray* system_tray,
+    system::TrayAudioDelegate* audio_delegate)
+    : TrayAudio(system_tray, audio_delegate),
+      audio_detail_view_(NULL) {
+}
+
+TrayAudioChromeOs::~TrayAudioChromeOs() {
+}
+
+void TrayAudioChromeOs::Update() {
+  TrayAudio::Update();
+
+  if (audio_detail_view_)
+    audio_detail_view_->Update();
+}
+
+views::View* TrayAudioChromeOs::CreateDetailedView(user::LoginStatus status) {
+  if (!ash::switches::ShowAudioDeviceMenu() || pop_up_volume_view_) {
+    volume_view_ = new tray::VolumeView(this, *audio_delegate_, false);
+    return volume_view_;
+  } else {
+    Shell::GetInstance()->metrics()->RecordUserMetricsAction(
+        ash::UMA_STATUS_AREA_DETAILED_AUDIO_VIEW);
+    audio_detail_view_ =
+        new tray::AudioDetailedView(this, status);
+    return audio_detail_view_;
+  }
+}
+
+void TrayAudioChromeOs::DestroyDetailedView() {
+  if (audio_detail_view_) {
+    audio_detail_view_ = NULL;
+  } else if (volume_view_) {
+    volume_view_ = NULL;
+    pop_up_volume_view_ = false;
+  }
+}
+
+}  // namespace internal
+}  // namespace ash