ash: Use system tray mojo interface to show system update tray icon

ash/common/system/tray/system_tray_delegate.cc

Index: ash/common/system/tray/system_tray_delegate.cc
diff --git a/ash/common/system/tray/system_tray_delegate.cc b/ash/common/system/tray/system_tray_delegate.cc
index 69ebf40e338dab0aa93b95198e41cacb1e9a189e..e3ba5b9c9bdbc47c13ef25d54b2efd61f9660d8d 100644
--- a/ash/common/system/tray/system_tray_delegate.cc
+++ b/ash/common/system/tray/system_tray_delegate.cc
@@ -17,13 +17,6 @@ BluetoothDeviceInfo::BluetoothDeviceInfo(const BluetoothDeviceInfo& other) =
 
 BluetoothDeviceInfo::~BluetoothDeviceInfo() {}
 
-UpdateInfo::UpdateInfo()
-    : severity(UPDATE_NONE),
-      update_required(false),
-      factory_reset_required(false) {}
-
-UpdateInfo::~UpdateInfo() {}
-
 SystemTrayDelegate::SystemTrayDelegate() {}
 
 SystemTrayDelegate::~SystemTrayDelegate() {}
@@ -66,12 +59,6 @@ bool SystemTrayDelegate::IsUserChild() const {
   return false;
 }
 
-void SystemTrayDelegate::GetSystemUpdateInfo(UpdateInfo* info) const {
-  info->severity = UpdateInfo::UPDATE_NONE;
-  info->update_required = false;
-  info->factory_reset_required = false;
-}
-
 bool SystemTrayDelegate::ShouldShowSettings() const {
   return false;
 }