Move ash tray audio UI code from ash/system/audio to ash/system/chromeos/audio.

ash/system/tray/system_tray.cc

Index: ash/system/tray/system_tray.cc
diff --git a/ash/system/tray/system_tray.cc b/ash/system/tray/system_tray.cc
index cfe37300867fdab6ed6e0dbcc427e8b9444024b9..8cbfddc0759a068bb27535d90eb770fccc9f4bc2 100644
--- a/ash/system/tray/system_tray.cc
+++ b/ash/system/tray/system_tray.cc
@@ -9,7 +9,6 @@
 #include "ash/shell.h"
 #include "ash/shell/panel_window.h"
 #include "ash/shell_window_ids.h"
-#include "ash/system/audio/tray_volume.h"
 #include "ash/system/bluetooth/tray_bluetooth.h"
 #include "ash/system/brightness/tray_brightness.h"
 #include "ash/system/date/tray_date.h"
@@ -51,6 +50,7 @@
 #include "ui/views/view.h"
 
 #if defined(OS_CHROMEOS)
+#include "ash/system/chromeos/audio/tray_volume.h"
 #include "ash/system/chromeos/enterprise/tray_enterprise.h"
 #include "ash/system/chromeos/network/tray_network.h"
 #include "ash/system/chromeos/network/tray_sms.h"
@@ -162,9 +162,9 @@ void SystemTray::CreateItems(SystemTrayDelegate* delegate) {
 #if defined(OS_CHROMEOS)
   AddTrayItem(new internal::TrayDisplay(this));
   AddTrayItem(new internal::TrayScreenCapture(this));
+  AddTrayItem(new internal::TrayVolume(this));
 #endif
 #if !defined(OS_WIN)
-  AddTrayItem(new internal::TrayVolume(this));
   AddTrayItem(new internal::TrayBrightness(this));
   AddTrayItem(new internal::TrayCapsLock(this));
 #endif