Revert of 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 e3ba5b9c9bdbc47c13ef25d54b2efd61f9660d8d..69ebf40e338dab0aa93b95198e41cacb1e9a189e 100644
--- a/ash/common/system/tray/system_tray_delegate.cc
+++ b/ash/common/system/tray/system_tray_delegate.cc
@@ -16,6 +16,13 @@
     default;
 
 BluetoothDeviceInfo::~BluetoothDeviceInfo() {}
+
+UpdateInfo::UpdateInfo()
+    : severity(UPDATE_NONE),
+      update_required(false),
+      factory_reset_required(false) {}
+
+UpdateInfo::~UpdateInfo() {}
 
 SystemTrayDelegate::SystemTrayDelegate() {}
 
@@ -57,6 +64,12 @@
 
 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 {