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

ash/system/audio/volume_view.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 ASH_SYSTEM_AUDIO_VOLUME_VIEW_H_
+#define ASH_SYSTEM_AUDIO_VOLUME_VIEW_H_
+
+#include "ash/system/tray/actionable_view.h"
+#include "ui/gfx/font.h"
+#include "ui/views/controls/button/button.h"
+#include "ui/views/controls/slider.h"
+
+namespace views {
+class View;
+class ImageView;
+}
+
+namespace ash {
+
+class SystemTrayItem;
+
+namespace system {
+class TrayAudioDelegate;
+}
+
+namespace internal {
+
+class HoverHighlightView;
+
+namespace tray {
+
+class BarSeparator;
+class VolumeButton;
+class VolumeSlider;
+
+class VolumeView : public ActionableView,
+                   public views::ButtonListener,
+                   public views::SliderListener {
+ public:
+  VolumeView(SystemTrayItem* owner,
+             system::TrayAudioDelegate& audio_delegate,

[jennyz, 2014/02/14 21:36:43]

Why not just pass system::TrayAudioDelegate*?

[zturner, 2014/02/15 00:57:45]

Done.

+             bool is_default_view);
+
+  virtual ~VolumeView();
+
+  void Update();
+
+  // Sets volume level on slider_, |percent| is ranged from [0.00] to [1.00].
+  void SetVolumeLevel(float percent);
+
+ private:
+  // Updates bar_, device_type_ icon, and more_ buttons.
+  void UpdateDeviceTypeAndMore();
+  void HandleVolumeUp(float percent);
+  void HandleVolumeDown(float percent);
+
+  // Overridden from views::View.
+  virtual void Layout() OVERRIDE;
+
+  // Overridden from views::ButtonListener.
+  virtual void ButtonPressed(views::Button* sender,
+                             const ui::Event& event) OVERRIDE;
+
+  // Overridden from views::SliderListener.
+  void SliderValueChanged(views::Slider* sender,
+                          float value,
+                          float old_value,
+                          views::SliderChangeReason reason);
+
+  // Overriden from ActionableView.
+  virtual bool PerformAction(const ui::Event& event) OVERRIDE;
+
+  SystemTrayItem* owner_;
+  system::TrayAudioDelegate& audio_delegate_;
+  VolumeButton* icon_;
+  VolumeSlider* slider_;
+  BarSeparator* bar_;
+  views::ImageView* device_type_;
+  views::ImageView* more_;
+  bool is_default_view_;
+
+  DISALLOW_COPY_AND_ASSIGN(VolumeView);
+};
+
+}  // namespace tray
+}  // namespace internal
+}  // namespace ash
+
+#endif

[jennyz, 2014/02/14 21:36:43]

Please add // ASH_SYSTEM_AUDIO_VOLUME_VIEW_H_ after #endif.