Update a11y of volume row in CrOS system menu.

ash/common/system/chromeos/audio/tray_audio_delegate.h

Index: ash/common/system/chromeos/audio/tray_audio_delegate.h
diff --git a/ash/common/system/chromeos/audio/tray_audio_delegate.h b/ash/common/system/chromeos/audio/tray_audio_delegate.h
index 4d5e343d787dcd1c620cb98ccb507532b532ef04..39d4b2a948bc7f8c9ae3b44f0a20fa02e049ad35 100644
--- a/ash/common/system/chromeos/audio/tray_audio_delegate.h
+++ b/ash/common/system/chromeos/audio/tray_audio_delegate.h
@@ -30,11 +30,6 @@ class TrayAudioDelegate {
   // should be muted.
   virtual int GetOutputDefaultVolumeMuteLevel() = 0;
 
-  // Gets the non-MD icon to use for the active output device.
-  // TODO(mohsen): Remove this once material design is enabled by default. See
-  // https://crbug.com/614453.
-  virtual int GetActiveOutputDeviceIconId() = 0;
-
   // Gets the MD icon to use for the active output device.
   virtual const gfx::VectorIcon& GetActiveOutputDeviceVectorIcon() = 0;