Refactor AddScrollListItem() in system menu detailed views

ash/system/tray/tri_view.cc

Index: ash/system/tray/tri_view.cc
diff --git a/ash/system/tray/tri_view.cc b/ash/system/tray/tri_view.cc
index a25ce00bf815d9aea04574a5c40ae9f4cfe73f97..09d39f6cbe3fd8cc84396c79c646a91fc5b85f5e 100644
--- a/ash/system/tray/tri_view.cc
+++ b/ash/system/tray/tri_view.cc
@@ -110,6 +110,10 @@ void TriView::AddView(Container container, views::View* view) {
   GetContainer(container)->AddChildView(view);
 }
 
+void TriView::RemoveView(Container container, views::View* view) {
+  GetContainer(container)->RemoveChildView(view);
+}
+
 void TriView::RemoveAllChildren(Container container, bool delete_children) {
   GetContainer(container)->RemoveAllChildViews(delete_children);
 }