Protect against lifecycle updates that delete a layout object for autoscroll

third_party/WebKit/Source/core/page/AutoscrollController.cpp

 /*
  * Copyright (C) 2013 Google Inc. All rights reserved.
  * Copyright (C) 2006, 2007, 2008, 2009, 2010, 2011 Apple Inc. All rights
  * reserved.
  * Copyright (C) 2006 Alexey Proskuryakov (ap@webkit.org)
  * Copyright (C) 2012 Digia Plc. and/or its subsidiary(-ies)
  *
  * Redistribution and use in source and binary forms, with or without
  * modification, are permitted provided that the following conditions
  * are met:
@@ skipping 58 matching lines @@
     const LayoutBox* layout_object) const {
   return autoscroll_layout_object_ == layout_object;
 }
 
 void AutoscrollController::StartAutoscrollForSelection(
     LayoutObject* layout_object) {
   // We don't want to trigger the autoscroll or the middleClickAutoscroll if
   // it's already active.
   if (autoscroll_type_ != kNoAutoscroll)
     return;
-  if (layout_object)
-    layout_object->GetFrameView()->UpdateAllLifecyclePhasesExceptPaint();
   LayoutBox* scrollable = LayoutBox::FindAutoscrollable(layout_object);
   if (!scrollable)
     scrollable =
         layout_object->IsListBox() ? ToLayoutListBox(layout_object) : nullptr;
   if (!scrollable)
     return;
 
   pressed_layout_object_ = layout_object && layout_object->IsBox()
                                ? ToLayoutBox(layout_object)
                                : nullptr;
@@ skipping 322 matching lines @@
   } else if (east) {
     view->SetCursor(EastPanningCursor());
   } else if (west) {
     view->SetCursor(WestPanningCursor());
   } else {
     view->SetCursor(MiddlePanningCursor());
   }
 }
 
 }  // namespace blink