mash: Migrate tray date view to //ash/common types

ash/common/system/tray/system_tray_delegate.h

Index: ash/common/system/tray/system_tray_delegate.h
diff --git a/ash/common/system/tray/system_tray_delegate.h b/ash/common/system/tray/system_tray_delegate.h
index 4fd79e4a5054e2f09d6c486dc97c49ec8397644f..2aaa642588d4d31fc92829f7539446a8255d9309 100644
--- a/ash/common/system/tray/system_tray_delegate.h
+++ b/ash/common/system/tray/system_tray_delegate.h
@@ -232,6 +232,9 @@ class ASH_EXPORT SystemTrayDelegate {
   // Attempts to restart the system for update.
   virtual void RequestRestartForUpdate();
 
+  // Attempts to shut down the system.
+  virtual void RequestShutdown();
+
   // Returns a list of available bluetooth devices.
   virtual void GetAvailableBluetoothDevices(BluetoothDeviceList* devices);