Fix tooltips for Chrome OS shelf overflow icons.

ash/shelf/overflow_bubble_view.cc

Index: ash/shelf/overflow_bubble_view.cc
diff --git a/ash/shelf/overflow_bubble_view.cc b/ash/shelf/overflow_bubble_view.cc
index ef288eb278e4bdaccdd316eaa86446b51ac735aa..55bd4ce227137b6b9a904ac4af686b45e4997085 100644
--- a/ash/shelf/overflow_bubble_view.cc
+++ b/ash/shelf/overflow_bubble_view.cc
@@ -39,7 +39,6 @@ OverflowBubbleView::~OverflowBubbleView() {}
 void OverflowBubbleView::InitOverflowBubble(views::View* anchor,
                                             ShelfView* shelf_view) {
   shelf_view_ = shelf_view;
-  AddChildView(shelf_view_);
 
   SetAnchorView(anchor);
   set_arrow(GetBubbleArrow());
@@ -59,6 +58,7 @@ void OverflowBubbleView::InitOverflowBubble(views::View* anchor,
       anchor->GetWidget()->GetNativeWindow()->GetRootWindow(),
       kShellWindowId_ShelfBubbleContainer));
   views::BubbleDelegateView::CreateBubble(this);
+  AddChildView(shelf_view_);
 }
 
 bool OverflowBubbleView::IsHorizontalAlignment() const {