Revert of Adding split view divider widget.

athena/util/drag_handle.h

-// Copyright 2014 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 ATHENA_UTIL_DRAG_HANDLE_H_
-#define ATHENA_UTIL_DRAG_HANDLE_H_
-
-#include "athena/athena_export.h"
-
-namespace views {
-class View;
-}
-
-namespace athena {
-class DragHandleScrollDelegate {
- public:
-  virtual ~DragHandleScrollDelegate() {}
-
-  // Beginning of a scroll gesture.
-  virtual void HandleScrollBegin(float delta) = 0;
-
-  // End of the current scroll gesture.
-  virtual void HandleScrollEnd() = 0;
-
-  // Update of the scroll position for the currently active scroll gesture.
-  virtual void HandleScrollUpdate(float delta) = 0;
-};
-
-enum DragHandleScrollDirection { DRAG_HANDLE_VERTICAL, DRAG_HANDLE_HORIZONTAL };
-
-// Creates a handle view which notifies the delegate of the scrolls performed on
-// it.
-ATHENA_EXPORT views::View* CreateDragHandleView(
-    DragHandleScrollDirection scroll_direction,
-    DragHandleScrollDelegate* delegate,
-    int preferred_width,
-    int preferred_height);
-
-}  // namespace athena
-
-#endif  // ATHENA_UTIL_DRAG_HANDLE_H_