Implement PaintLayer::scrollsWithViewport for SPv2.

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 59 matching lines @@
     const LayoutBox* layoutObject) const {
   return m_autoscrollLayoutObject == layoutObject;
 }
 
 void AutoscrollController::startAutoscrollForSelection(
     LayoutObject* layoutObject) {
   // We don't want to trigger the autoscroll or the middleClickAutoscroll if
   // it's already active.
   if (m_autoscrollType != NoAutoscroll)
     return;
+  if (layoutObject)
+    layoutObject->frameView()->updateAllLifecyclePhasesExceptPaint();
   LayoutBox* scrollable = LayoutBox::findAutoscrollable(layoutObject);
   if (!scrollable)
     scrollable =
         layoutObject->isListBox() ? toLayoutListBox(layoutObject) : nullptr;
   if (!scrollable)
     return;
 
   m_pressedLayoutObject = layoutObject && layoutObject->isBox()
                               ? toLayoutBox(layoutObject)
                               : nullptr;
@@ skipping 66 matching lines @@
   if (!dropTargetNode || !dropTargetNode->layoutObject()) {
     stopAutoscroll();
     return;
   }
 
   if (m_autoscrollLayoutObject &&
       m_autoscrollLayoutObject->frame() !=
           dropTargetNode->layoutObject()->frame())
     return;
 
+  dropTargetNode->layoutObject()
+      ->frameView()
+      ->updateAllLifecyclePhasesExceptPaint();
+
   LayoutBox* scrollable =
       LayoutBox::findAutoscrollable(dropTargetNode->layoutObject());
   if (!scrollable) {
     stopAutoscroll();
     return;
   }
 
   Page* page = scrollable->frame() ? scrollable->frame()->page() : nullptr;
   if (!page) {
     stopAutoscroll();
@@ skipping 229 matching lines @@
   } else if (east) {
     view->setCursor(eastPanningCursor());
   } else if (west) {
     view->setCursor(westPanningCursor());
   } else {
     view->setCursor(middlePanningCursor());
   }
 }
 
 }  // namespace blink