ui: Cleanup class/struct forward declarations

ui/views/controls/tree/tree_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_CONTROLS_TREE_TREE_VIEW_VIEWS_H_
 #define UI_VIEWS_CONTROLS_TREE_TREE_VIEW_VIEWS_H_
 
 #include <memory>
 #include <vector>
 
 #include "base/compiler_specific.h"
 #include "base/macros.h"
 #include "ui/base/models/tree_node_model.h"
 #include "ui/gfx/font_list.h"
 #include "ui/gfx/image/image_skia.h"
 #include "ui/views/controls/prefix_delegate.h"
 #include "ui/views/controls/textfield/textfield_controller.h"
 #include "ui/views/focus/focus_manager.h"
 #include "ui/views/view.h"
 
 namespace gfx {
 class Rect;
 }  // namespace gfx
 
 namespace views {
 
 class PrefixSelector;
-class ScrollView;
 class Textfield;
 class TreeViewController;
 
 // TreeView displays hierarchical data as returned from a TreeModel. The user
 // can expand, collapse and edit the items. A Controller may be attached to
 // receive notification of selection changes and restrict editing.
 //
 // Note on implementation. This implementation doesn't scale well. In particular
 // it does not store any row information, but instead calculates it as
 // necessary. But it's more than adequate for current uses.
@@ skipping 372 matching lines @@
   int text_offset_;
 
   std::unique_ptr<PrefixSelector> selector_;
 
   DISALLOW_COPY_AND_ASSIGN(TreeView);
 };
 
 }  // namespace views
 
 #endif  // UI_VIEWS_CONTROLS_TREE_TREE_VIEW_VIEWS_H_