Refactor AddScrollListItem() in system menu detailed views

ash/system/audio/audio_detailed_view.h

 // 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.
 
 #ifndef ASH_SYSTEM_AUDIO_AUDIO_DETAILED_VIEW_H_
 #define ASH_SYSTEM_AUDIO_AUDIO_DETAILED_VIEW_H_
 
 #include <map>
 
 #include "ash/system/tray/tray_details_view.h"
 #include "base/macros.h"
 #include "chromeos/audio/audio_device.h"
 
 namespace gfx {
 struct VectorIcon;
 }
 
-namespace views {
-class View;
-}
-
 namespace ash {
-class HoverHighlightView;
-
 namespace tray {
 
 class AudioDetailedView : public TrayDetailsView {
  public:
   explicit AudioDetailedView(SystemTrayItem* owner);
 
   ~AudioDetailedView() override;
 
   void Update();
 
  private:
-  // Helper functions to add non-clickable header rows within the scrollable
+  // Helper function to add non-clickable header rows within the scrollable
   // list.
-  void AddInputHeader();
-  void AddOutputHeader();
-  void AddScrollListInfoItem(int text_id, const gfx::VectorIcon& icon);
-
-  HoverHighlightView* AddScrollListItem(const base::string16& text,
-                                        bool highlight,
-                                        bool checked);
+  void AddAudioSubHeader(const gfx::VectorIcon& icon, int text_id);
 
   void CreateItems();
 
   void UpdateScrollableList();
   void UpdateAudioDevices();
 
   // TrayDetailsView:
   void HandleViewClicked(views::View* view) override;
 
   typedef std::map<views::View*, chromeos::AudioDevice> AudioDeviceMap;
 
   chromeos::AudioDeviceList output_devices_;
   chromeos::AudioDeviceList input_devices_;
   AudioDeviceMap device_map_;
 
   DISALLOW_COPY_AND_ASSIGN(AudioDetailedView);
 };
 
 }  // namespace tray
 }  // namespace ash
 
 #endif  // ASH_SYSTEM_AUDIO_AUDIO_DETAILED_VIEW_H_