Add LauncherItem for TaskManager Dialog

ash/shelf/shelf_view.cc

Index: ash/shelf/shelf_view.cc
diff --git a/ash/shelf/shelf_view.cc b/ash/shelf/shelf_view.cc
index b387e255bb57d2568e5202fe57c36e90b2aa83a5..368484389a3daf4e69bd6306a2fdd89a5ebdca41 100644
--- a/ash/shelf/shelf_view.cc
+++ b/ash/shelf/shelf_view.cc
@@ -1235,8 +1235,9 @@ void ShelfView::FinalizeRipOffDrag(bool cancel) {
 ShelfView::RemovableState ShelfView::RemovableByRipOff(int index) {
   DCHECK(index >= 0 && index < model_->item_count());
   LauncherItemType type = model_->items()[index].type;
-  if (type == TYPE_APP_LIST || !delegate_->CanPin())
+  if (type == TYPE_APP_LIST || type == TYPE_DIALOG || !delegate_->CanPin())
     return NOT_REMOVABLE;
+
   std::string app_id =
       delegate_->GetAppIDForLauncherID(model_->items()[index].id);
   // Note: Only pinned app shortcuts can be removed!