Move shelf item tooltip flag from delegate to item.

ash/common/shelf/app_list_shelf_item_delegate.cc

 // Copyright 2013 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #include "ash/common/shelf/app_list_shelf_item_delegate.h"
 
 #include "ash/common/shelf/shelf_model.h"
 #include "ash/common/wm_shell.h"
 #include "base/memory/ptr_util.h"
 #include "grit/ash_strings.h"
@@ skipping 45 matching lines @@
 }
 
 bool AppListShelfItemDelegate::IsDraggable() {
   return false;
 }
 
 bool AppListShelfItemDelegate::CanPin() const {
   return true;
 }
 
-bool AppListShelfItemDelegate::ShouldShowTooltip() {
-  return true;
-}
-
 void AppListShelfItemDelegate::Close() {}
 
 }  // namespace ash