[Ash MD] Remove pre-MD code from TrayImageItem and subclasses

ash/common/system/chromeos/audio/tray_audio.cc

 // 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.
 
 #include "ash/common/system/chromeos/audio/tray_audio.h"
 
 #include "ash/common/system/chromeos/audio/audio_detailed_view.h"
 #include "ash/common/system/chromeos/audio/tray_audio_delegate_chromeos.h"
 #include "ash/common/system/chromeos/audio/volume_view.h"
 #include "ash/common/system/tray/system_tray.h"
 #include "ash/common/system/tray/tray_constants.h"
 #include "ash/common/wm_shell.h"
 #include "ash/common/wm_window.h"
 #include "ash/root_window_controller.h"
 #include "chromeos/dbus/dbus_thread_manager.h"
-#include "grit/ash_resources.h"
 #include "ui/display/display.h"
 #include "ui/display/manager/managed_display_info.h"
 #include "ui/display/screen.h"
 #include "ui/views/view.h"
 
 namespace ash {
 
 using chromeos::CrasAudioHandler;
 using chromeos::DBusThreadManager;
 using system::TrayAudioDelegate;
 using system::TrayAudioDelegateChromeOs;
 
 TrayAudio::TrayAudio(SystemTray* system_tray)
-    : TrayImageItem(system_tray, IDR_AURA_UBER_TRAY_VOLUME_MUTE, UMA_AUDIO),
+    : TrayImageItem(system_tray, kSystemTrayVolumeMuteIcon, UMA_AUDIO),
       audio_delegate_(new TrayAudioDelegateChromeOs()),
       volume_view_(nullptr),
       pop_up_volume_view_(false),
       audio_detail_view_(nullptr) {
   if (CrasAudioHandler::IsInitialized())
     CrasAudioHandler::Get()->AddAudioObserver(this);
   display::Screen::GetScreen()->AddObserver(this);
   DBusThreadManager::Get()->GetPowerManagerClient()->AddObserver(this);
 }
 
@@ skipping 160 matching lines @@
     volume_view_->SetVolumeLevel(
         static_cast<float>(audio_delegate_->GetOutputVolumeLevel()) / 100.0f);
     volume_view_->Update();
   }
 
   if (audio_detail_view_)
     audio_detail_view_->Update();
 }
 
 }  // namespace ash