Have Frame::tree() return a reference

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 330 matching lines @@
 }
 
 // In order to do a DFS cross-frame walk of the RenderLayer tree, we need to know which
 // RenderLayers have child frames inside of them. This computes a mapping for the
 // current frame which we can consult while walking the layers of that frame.
 // Whenever we descend into a new frame, a new map will be created.
 typedef HashMap<const RenderLayer*, Vector<const Frame*> > LayerFrameMap;
 static void makeLayerChildFrameMap(const Frame* currentFrame, LayerFrameMap* map)
 {
     map->clear();
-    const FrameTree* tree = currentFrame->tree();
-    for (const Frame* child = tree->firstChild(); child; child = child->tree()->nextSibling()) {
+    const FrameTree& tree = currentFrame->tree();
+    for (const Frame* child = tree.firstChild(); child; child = child->tree().nextSibling()) {
         const RenderLayer* containingLayer = child->ownerRenderer()->enclosingLayer();
         LayerFrameMap::iterator iter = map->find(containingLayer);
         if (iter == map->end())
             iter = map->add(containingLayer, Vector<const Frame*>()).iterator;
         iter->value.append(child);
     }
 }
 
 static void convertLayerRectsToEnclosingCompositedLayerRecursive(
     const RenderLayer* curLayer,
@@ skipping 262 matching lines @@
         for (HashSet<RefPtr<Widget> >::const_iterator it = children->begin(), end = children->end(); it != end; ++it) {
             if (!(*it)->isPluginView())
                 continue;
 
             PluginView* pluginView = toPluginView((*it).get());
             if (pluginView->wantsWheelEvents())
                 shouldHandleScrollGestureOnMainThreadRegion.unite(pluginView->frameRect());
         }
     }
 
-    FrameTree* tree = frame->tree();
-    for (Frame* subFrame = tree->firstChild(); subFrame; subFrame = subFrame->tree()->nextSibling())
+    const FrameTree& tree = frame->tree();
+    for (Frame* subFrame = tree.firstChild(); subFrame; subFrame = subFrame->tree().nextSibling())
         shouldHandleScrollGestureOnMainThreadRegion.unite(computeShouldHandleScrollGestureOnMainThreadRegion(subFrame, offset));
 
     return shouldHandleScrollGestureOnMainThreadRegion;
 }
 
 static void accumulateDocumentTouchEventTargetRects(LayerHitTestRects& rects, const Document* document)
 {
     ASSERT(document);
     if (!document->touchEventTargets())
         return;
@@ skipping 46 matching lines @@
     if (!document || !document->view())
         return;
 
     accumulateDocumentTouchEventTargetRects(rects, document);
 }
 
 unsigned ScrollingCoordinator::computeCurrentWheelEventHandlerCount()
 {
     unsigned wheelEventHandlerCount = 0;
 
-    for (Frame* frame = m_page->mainFrame(); frame; frame = frame->tree()->traverseNext()) {
+    for (Frame* frame = m_page->mainFrame(); frame; frame = frame->tree().traverseNext()) {
         if (frame->document())
             wheelEventHandlerCount += WheelController::from(frame->document())->wheelEventHandlerCount();
     }
 
     return wheelEventHandlerCount;
 }
 
 void ScrollingCoordinator::frameViewWheelEventHandlerCountChanged(FrameView* frameView)
 {
     ASSERT(isMainThread());
@@ skipping 148 matching lines @@
         stringBuilder.resize(stringBuilder.length() - 2);
     return stringBuilder.toString();
 }
 
 String ScrollingCoordinator::mainThreadScrollingReasonsAsText() const
 {
     return mainThreadScrollingReasonsAsText(mainThreadScrollingReasons());
 }
 
 } // namespace WebCore