Remove ScheduleAnimation proxy methods, call HostWindow directly

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

Index: third_party/WebKit/Source/core/paint/PaintLayerScrollableArea.cpp
diff --git a/third_party/WebKit/Source/core/paint/PaintLayerScrollableArea.cpp b/third_party/WebKit/Source/core/paint/PaintLayerScrollableArea.cpp
index db92faede365db37f0c8044b9e23695cabcb886c..66dfe99b5257136f67762e73a0db8183c0d9890a 100644
--- a/third_party/WebKit/Source/core/paint/PaintLayerScrollableArea.cpp
+++ b/third_party/WebKit/Source/core/paint/PaintLayerScrollableArea.cpp
@@ -1902,7 +1902,11 @@ bool PaintLayerScrollableArea::VisualViewportSuppliesScrollbars() const {
 }
 
 bool PaintLayerScrollableArea::ScheduleAnimation() {
-  return Box().GetFrame()->ScheduleAnimation(GetHostWindow());
+  if (HostWindow* window = GetHostWindow()) {
+    window->ScheduleAnimation(Box().GetFrame());
+    return true;
+  }
+  return false;
 }
 
 void PaintLayerScrollableArea::ResetRebuildScrollbarLayerFlags() {