Consolidate some more ash tray constants.

ash/common/system/tray/tray_background_view.cc

Index: ash/common/system/tray/tray_background_view.cc
diff --git a/ash/common/system/tray/tray_background_view.cc b/ash/common/system/tray/tray_background_view.cc
index fb988555461b5df0a564ecaa62eaf36c381cc646..6cf15532cdae0c29a9630291907e3b236f3cf06c 100644
--- a/ash/common/system/tray/tray_background_view.cc
+++ b/ash/common/system/tray/tray_background_view.cc
@@ -415,8 +415,7 @@ TrayBackgroundView::CreateInkDropHighlight() const {
   // correctly, so the extra highlight would be clipped.
   // TODO(mohsen): Remove this extra size when resize is handled properly (see
   // https://crbug.com/669253).
-  const int icon_size =
-      kTrayIconSize + 2 * GetTrayConstant(TRAY_IMAGE_ITEM_PADDING);
+  const int icon_size = kTrayIconSize + 2 * kTrayImageItemPadding;
   bounds.set_width(bounds.width() + 2 * icon_size);
   bounds.set_height(bounds.height() + 2 * icon_size);
   std::unique_ptr<views::InkDropHighlight> highlight(