[Refactor] Moved scrollbar creation and deletion to ScrollbarManager

third_party/WebKit/Source/core/paint/ScrollbarManager.h

 // Copyright 2016 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 ScrollbarManager_h
 #define ScrollbarManager_h
 
 #include "core/CoreExport.h"
 #include "platform/scroll/ScrollableArea.h"
 
@@ skipping 16 matching lines @@
   }
   bool HasHorizontalScrollbar() const { return HorizontalScrollbar(); }
   bool HasVerticalScrollbar() const { return VerticalScrollbar(); }
 
   // These functions are used to create/destroy scrollbars.
   virtual void SetHasHorizontalScrollbar(bool has_scrollbar) = 0;
   virtual void SetHasVerticalScrollbar(bool has_scrollbar) = 0;
 
   DECLARE_VIRTUAL_TRACE();
 
- protected:
-  // TODO(ymalik): This can be made non-virtual since there's a lot of
-  // common code in subclasses.
-  virtual Scrollbar* CreateScrollbar(ScrollbarOrientation) = 0;
-  virtual void DestroyScrollbar(ScrollbarOrientation) = 0;
+  Scrollbar* CreateScrollbar(ScrollbarOrientation);
+
+  void DestroyScrollbar(ScrollbarOrientation);
 
  protected:
   Member<ScrollableArea> scrollable_area_;
 
   // The scrollbars associated with m_scrollableArea. Both can nullptr.
   Member<Scrollbar> h_bar_;
   Member<Scrollbar> v_bar_;
 
   unsigned h_bar_is_attached_ : 1;
   unsigned v_bar_is_attached_ : 1;
 };
 
 }  // namespace blink
 
 #endif  // ScrollbarManager_h