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

ui/app_list/views/apps_grid_view.cc

 // Copyright (c) 2012 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 "ui/app_list/views/apps_grid_view.h"
 
 #include <algorithm>
 #include <set>
 #include <string>
 
@@ skipping 438 matching lines @@
   drag_start_page_ = pagination_model_->selected_page();
   ExtractDragLocation(event, &drag_start_grid_view_);
   drag_view_start_ = gfx::Point(drag_view_->x(), drag_view_->y());
 }
 
 void AppsGridView::StartSettingUpSynchronousDrag() {
 #if defined(OS_WIN)
   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_)
     return;
 
   // Never create a second synchronous drag if the drag started in a folder.
   if (IsDraggingForReparentInRootLevelGridView())
     return;
 
   synchronous_drag_ = new SynchronousDrag(this, drag_view_, drag_view_offset_);
@@ skipping 1624 matching lines @@
 void AppsGridView::SetAsFolderDroppingTarget(const Index& target_index,
                                              bool is_target_folder) {
   AppListItemView* target_view =
       static_cast<AppListItemView*>(
           GetViewAtSlotOnCurrentPage(target_index.slot));
   if (target_view)
     target_view->SetAsAttemptedFolderTarget(is_target_folder);
 }
 
 }  // namespace app_list