Use mojo SystemTray interfaces for both mash and classic ash

ash/common/system/date/tray_date.cc

Index: ash/common/system/date/tray_date.cc
diff --git a/ash/common/system/date/tray_date.cc b/ash/common/system/date/tray_date.cc
index 93ef9ebefb73df477dec09acccca461366013589..0a712b4e426d78fd36e04e377b557f6e8a8e6569 100644
--- a/ash/common/system/date/tray_date.cc
+++ b/ash/common/system/date/tray_date.cc
@@ -8,7 +8,7 @@
 #include "ash/common/system/date/date_default_view.h"
 #include "ash/common/system/date/date_view.h"
 #include "ash/common/system/tray/system_tray.h"
-#include "ash/common/system/tray/system_tray_notifier.h"
+#include "ash/common/system/tray/system_tray_controller.h"
 #include "ash/common/system/tray/tray_item_view.h"
 #include "ash/common/wm_shell.h"
 
@@ -26,11 +26,11 @@ TrayDate::TrayDate(SystemTray* system_tray)
 #if defined(OS_CHROMEOS)
   system_clock_observer_.reset(new SystemClockObserver());
 #endif
-  WmShell::Get()->system_tray_notifier()->AddClockObserver(this);
+  WmShell::Get()->system_tray_controller()->AddClockObserver(this);
 }
 
 TrayDate::~TrayDate() {
-  WmShell::Get()->system_tray_notifier()->RemoveClockObserver(this);
+  WmShell::Get()->system_tray_controller()->RemoveClockObserver(this);
 }
 
 views::View* TrayDate::GetHelpButtonView() const {