Remove ScheduleAnimation proxy methods, call HostWindow directly

third_party/WebKit/Source/core/paint/PaintLayerScrollableArea.cpp

 /*
  * Copyright (C) 2006, 2007, 2008, 2009, 2010, 2011, 2012 Apple Inc. All rights
  * reserved.
  *
  * Portions are Copyright (C) 1998 Netscape Communications Corporation.
  *
  * Other contributors:
  *   Robert O'Callahan <roc+@cs.cmu.edu>
  *   David Baron <dbaron@fas.harvard.edu>
  *   Christian Biesinger <cbiesinger@gmail.com>
@@ skipping 1884 matching lines @@
     return false;
 
   const TopDocumentRootScrollerController& controller =
       GetLayoutBox()->GetDocument().GetPage()->GlobalRootScrollerController();
 
   return RootScrollerUtil::ScrollableAreaForRootScroller(
              controller.GlobalRootScroller()) == this;
 }
 
 bool PaintLayerScrollableArea::ScheduleAnimation() {
-  return Box().GetFrame()->ScheduleAnimation(GetHostWindow());
+  if (HostWindow* window = GetHostWindow()) {
+    window->ScheduleAnimation(Box().GetFrame());
+    return true;
+  }
+  return false;
 }
 
 void PaintLayerScrollableArea::ResetRebuildScrollbarLayerFlags() {
   rebuild_horizontal_scrollbar_layer_ = false;
   rebuild_vertical_scrollbar_layer_ = false;
 }
 
 CompositorAnimationHost* PaintLayerScrollableArea::GetCompositorAnimationHost()
     const {
   return layer_.GetLayoutObject().GetFrameView()->GetCompositorAnimationHost();
@@ skipping 217 matching lines @@
 
 void PaintLayerScrollableArea::DelayScrollOffsetClampScope::
     ClampScrollableAreas() {
   for (auto& scrollable_area : *needs_clamp_)
     scrollable_area->ClampScrollOffsetAfterOverflowChange();
   delete needs_clamp_;
   needs_clamp_ = nullptr;
 }
 
 }  // namespace blink