Move shelf item tooltip flag from delegate to item.

ash/common/shelf/shelf_item_delegate.h

Index: ash/common/shelf/shelf_item_delegate.h
diff --git a/ash/common/shelf/shelf_item_delegate.h b/ash/common/shelf/shelf_item_delegate.h
index 4dc6030d82a381cd023a1c29d82e172ba0465024..8cd6c1172b2ecfe13882edfc9280de7366f6ddc9 100644
--- a/ash/common/shelf/shelf_item_delegate.h
+++ b/ash/common/shelf/shelf_item_delegate.h
@@ -66,9 +66,6 @@ class ASH_EXPORT ShelfItemDelegate {
   // Whether the launcher item is draggable.
   virtual bool IsDraggable() = 0;
 
-  // Returns true if a tooltip should be shown.
-  virtual bool ShouldShowTooltip() = 0;
-
   // Closes all windows associated with this item.
   virtual void Close() = 0;
 };