Make spacing between uber tray items consistent with UI spec.

ash/system/tray/tray_image_item.cc

Index: ash/system/tray/tray_image_item.cc
diff --git a/ash/system/tray/tray_image_item.cc b/ash/system/tray/tray_image_item.cc
index 449cbd72c7a8d46d3171745b2c1b91be05fc6f59..fbef4205e933dc9c3e375f2a0a906186ef3ad51e 100644
--- a/ash/system/tray/tray_image_item.cc
+++ b/ash/system/tray/tray_image_item.cc
@@ -5,6 +5,7 @@
 #include "ash/system/tray/tray_image_item.h"
 
 #include "ash/system/tray/tray_item_view.h"
+#include "ash/system/tray/tray_views.h"
 #include "ui/base/resource/resource_bundle.h"
 #include "ui/gfx/image/image.h"
 #include "ui/views/controls/image_view.h"
@@ -45,6 +46,10 @@ views::View* TrayImageItem::CreateDetailedView(user::LoginStatus status) {
 void TrayImageItem::UpdateAfterLoginStatusChange(user::LoginStatus status) {
 }
 
+void TrayImageItem::UpdateAfterShelfAlignmentChange(ShelfAlignment alignment) {
+  SetTrayImageItemBorder(tray_view_, alignment);
+}
+
 void TrayImageItem::DestroyTrayView() {
   tray_view_ = NULL;
 }