Oilpan: improve ScrollableArea handling.

Source/core/page/scrolling/ScrollingCoordinator.cpp

 /*
  * Copyright (C) 2011 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 62 matching lines @@
 
 WebLayer* toWebLayer(blink::GraphicsLayer* layer)
 {
     return layer ? layer->platformLayer() : nullptr;
 }
 
 } // namespace
 
 namespace blink {
 
-PassOwnPtr<ScrollingCoordinator> ScrollingCoordinator::create(Page* page)
+PassOwnPtrWillBeRawPtr<ScrollingCoordinator> ScrollingCoordinator::create(Page* page)
 {
-    return adoptPtr(new ScrollingCoordinator(page));
+    return adoptPtrWillBeNoop(new ScrollingCoordinator(page));
 }
 
 ScrollingCoordinator::ScrollingCoordinator(Page* page)
     : m_page(page)
     , m_scrollGestureRegionIsDirty(false)
     , m_touchEventTargetRectsAreDirty(false)
     , m_shouldScrollOnMainThreadDirty(false)
     , m_wasFrameScrollable(false)
     , m_lastMainThreadScrollingReasons(0)
 {
 }
 
 ScrollingCoordinator::~ScrollingCoordinator()
 {
+    ASSERT(!m_page);
+}
+
+DEFINE_TRACE(ScrollingCoordinator)
+{
+    visitor->trace(m_page);
+#if ENABLE(OILPAN)
+    visitor->trace(m_horizontalScrollbars);
+    visitor->trace(m_verticalScrollbars);
+#endif
 }
 
 void ScrollingCoordinator::setShouldHandleScrollGestureOnMainThreadRegion(const Region& region)
 {
     if (!m_page->mainFrame()->isLocalFrame() || !m_page->deprecatedLocalMainFrame()->view())
         return;
     if (WebLayer* scrollLayer = toWebLayer(m_page->deprecatedLocalMainFrame()->view()->layerForScrolling())) {
         Vector<IntRect> rects = region.rects();
         WebVector<WebRect> webRects(rects.size());
         for (size_t i = 0; i < rects.size(); ++i)
@@ skipping 941 matching lines @@
     bool frameIsScrollable = frameView && frameView->isScrollable();
     if (frameIsScrollable != m_wasFrameScrollable)
         return true;
 
     if (WebLayer* scrollLayer = frameView ? toWebLayer(frameView->layerForScrolling()) : nullptr)
         return WebSize(frameView->contentsSize()) != scrollLayer->bounds();
     return false;
 }
 
 } // namespace blink