Disallow dragging app list folder to the taskbar for the Windows app list.

ui/app_list/views/apps_grid_view.cc

Index: ui/app_list/views/apps_grid_view.cc
diff --git a/ui/app_list/views/apps_grid_view.cc b/ui/app_list/views/apps_grid_view.cc
index 5a620a6270152c26c6b3aaf8ed0ec9a953d12074..f19b2d52b98a99957a6483982d8050e45616c0ec 100644
--- a/ui/app_list/views/apps_grid_view.cc
+++ b/ui/app_list/views/apps_grid_view.cc
@@ -456,6 +456,10 @@ void AppsGridView::StartSettingUpSynchronousDrag() {
   if (!delegate_)
     return;
 
+  // Folders can't be integrated with the OS.
+  if (IsFolderItem(drag_view_->item()))
+    return;
+
   // Favor the drag and drop host over native win32 drag. For the Win8/ash
   // launcher we want to have ashes drag and drop over win32's.
   if (drag_and_drop_host_)