Replace ShelfItemDelegate::GetTitle() with ShelfItem::title.

ash/shell/window_watcher_shelf_item_delegate.cc

Index: ash/shell/window_watcher_shelf_item_delegate.cc
diff --git a/ash/shell/window_watcher_shelf_item_delegate.cc b/ash/shell/window_watcher_shelf_item_delegate.cc
index 6c45e0971b61ff4009dafc2b6986aa5e74ec3f65..d50371bb4cdd9b44cfb0f956b1ff88ecc57dd653 100644
--- a/ash/shell/window_watcher_shelf_item_delegate.cc
+++ b/ash/shell/window_watcher_shelf_item_delegate.cc
@@ -31,10 +31,6 @@ ShelfItemDelegate::PerformedAction WindowWatcherShelfItemDelegate::ItemSelected(
   return kExistingWindowActivated;
 }
 
-base::string16 WindowWatcherShelfItemDelegate::GetTitle() {
-  return watcher_->GetWindowByID(id_)->GetTitle();
-}
-
 ShelfMenuModel* WindowWatcherShelfItemDelegate::CreateApplicationMenu(
     int event_flags) {
   return nullptr;