Move DropTargetEvent back to ui/base for the time being as it depends on OSExchangeData which I don…

ui/views/view.h

 // 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.
 
 #ifndef UI_VIEWS_VIEW_H_
 #define UI_VIEWS_VIEW_H_
 
 #include <algorithm>
 #include <map>
 #include <set>
 #include <string>
 #include <vector>
 
 #include "base/compiler_specific.h"
 #include "base/i18n/rtl.h"
 #include "base/logging.h"
 #include "base/memory/scoped_ptr.h"
 #include "build/build_config.h"
 #include "ui/base/accelerators/accelerator.h"
 #include "ui/base/accessibility/accessibility_types.h"
 #include "ui/base/dragdrop/drag_drop_types.h"
+#include "ui/base/dragdrop/drop_target_event.h"
 #include "ui/base/dragdrop/os_exchange_data.h"
 #include "ui/base/ui_base_types.h"
 #include "ui/compositor/layer_delegate.h"
 #include "ui/compositor/layer_owner.h"
 #include "ui/events/event.h"
 #include "ui/events/event_target.h"
 #include "ui/gfx/native_widget_types.h"
 #include "ui/gfx/rect.h"
 #include "ui/gfx/vector2d.h"
 #include "ui/views/background.h"
@@ skipping 1507 matching lines @@
   // Belongs to this view, but it's reference-counted on some platforms
   // so we can't use a scoped_ptr. It's dereferenced in the destructor.
   NativeViewAccessibility* native_view_accessibility_;
 
   DISALLOW_COPY_AND_ASSIGN(View);
 };
 
 }  // namespace views
 
 #endif  // UI_VIEWS_VIEW_H_