Move ScrollbarManager from core to platform and use as Scrollbar parent

third_party/WebKit/Source/platform/scroll/Scrollbar.cpp

 /*
  * Copyright (C) 2004, 2006, 2008 Apple Inc. All rights reserved.
  *
  * Redistribution and use in source and binary forms, with or without
  * modification, are permitted provided that the following conditions
  * are met:
  * 1. Redistributions of source code must retain the above copyright
  *    notice, this list of conditions and the following disclaimer.
  * 2. Redistributions in binary form must reproduce the above copyright
  *    notice, this list of conditions and the following disclaimer in the
@@ skipping 554 matching lines @@
     return true;
   return !scrollable_area_->ScrollbarsHidden();
 }
 
 bool Scrollbar::IsWindowActive() const {
   return scrollable_area_ && scrollable_area_->IsActive();
 }
 
 IntPoint Scrollbar::ConvertFromRootFrame(
     const IntPoint& point_in_root_frame) const {
-  if (const FrameViewBase* parent = Parent()) {
+  if (const ScrollbarManager* parent = Parent()) {
     IntPoint parent_point = parent->ConvertFromRootFrame(point_in_root_frame);
     if (scrollable_area_) {
       return scrollable_area_->ConvertFromContainingFrameViewBaseToScrollbar(
           *this, parent_point);
     }
   }
 
   return point_in_root_frame;
 }
 
@@ skipping 48 matching lines @@
     invalid_parts = kAllParts;
   if (invalid_parts & ~kThumbPart)
     track_needs_repaint_ = true;
   if (invalid_parts & kThumbPart)
     thumb_needs_repaint_ = true;
   if (scrollable_area_)
     scrollable_area_->SetScrollbarNeedsPaintInvalidation(Orientation());
 }
 
 }  // namespace blink