Enable the volume slider in Ash for windows.

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 59f69707885d7e509a3cb5dc91e5f9b665557c36..344fe587ac1b80c064710b109691d2d81170a244 100644
--- a/ash/system/tray/system_tray.cc
+++ b/ash/system/tray/system_tray.cc
@@ -62,6 +62,9 @@
 #include "ash/system/chromeos/tray_display.h"
 #include "ash/system/chromeos/tray_tracing.h"
 #include "ui/message_center/message_center.h"
+#elif defined(OS_WIN)
+#include "ash/system/win/audio/tray_audio_win.h"
+#include "media/audio/win/core_audio_util_win.h"
 #endif
 
 using views::TrayBubbleView;
@@ -204,6 +207,8 @@ void SystemTray::CreateItems(SystemTrayDelegate* delegate) {
   AddTrayItem(tray_date_);
 #elif defined(OS_WIN)
   AddTrayItem(tray_accessibility_);
+  if (media::CoreAudioUtil::IsSupported())

[henrika (OOO until Aug 14), 2014/02/26 09:10:05]

Just checking. What happens on Windows XP here?

[zturner, 2014/02/26 17:50:29]

"Windows Ash" is mostly synonymous with "Chrome Windows 8 mode".  So as the name
implies, you cannot run Ash on any version of Windows prior to 8 (actually you
can make it work on Win7, but it's not a supported configuration, and may be
broken).

+    AddTrayItem(new internal::TrayAudioWin(this));
   AddTrayItem(new internal::TrayUpdate(this));
   AddTrayItem(tray_date_);
 #elif defined(OS_LINUX)