More work to make ash_unittests pass when we require context.

ash/drag_drop/drag_image_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 ASH_DRAG_DROP_DRAG_IMAGE_VIEW_H_
 #define ASH_DRAG_DROP_DRAG_IMAGE_VIEW_H_
 
 #include "ui/views/controls/image_view.h"
 
 namespace views {
 class Widget;
 }
 
 namespace ash {
 namespace internal {
 
 class DragImageView : public views::ImageView {
  public:
-  DragImageView();
+  explicit DragImageView(gfx::NativeView context);
   virtual ~DragImageView();
 
   // Sets the bounds of the native widget in screen
   // coordinates.
   // TODO(oshima): Looks like this is root window's
   // coordinate. Change this to screen's coordinate.
   void SetBoundsInScreen(const gfx::Rect& bounds);
 
   // Sets the position of the native widget.
   void SetScreenPosition(const gfx::Point& position);
 
   // Sets the visibility of the native widget.
   void SetWidgetVisible(bool visible);
 
  private:
   // Overridden from views::ImageView.
   virtual void OnPaint(gfx::Canvas* canvas) OVERRIDE;
 
   scoped_ptr<views::Widget> widget_;
   gfx::Size widget_size_;
 
   DISALLOW_COPY_AND_ASSIGN(DragImageView);
 };
 
 }  // namespace internal
 }  // namespace ash
 
 #endif  // ASH_DRAG_DROP_DRAG_IMAGE_VIEW_H_