Have Frame::tree() return a reference

Source/core/loader/HistoryController.cpp

Index: Source/core/loader/HistoryController.cpp
diff --git a/Source/core/loader/HistoryController.cpp b/Source/core/loader/HistoryController.cpp
index a506ffd3a554b082aa6d79cbc08bbdcea12056d8..d1b5a10aea4beecab21b08f041c4b260ea13699d 100644
--- a/Source/core/loader/HistoryController.cpp
+++ b/Source/core/loader/HistoryController.cpp
@@ -113,7 +113,7 @@ void HistoryController::saveDocumentAndScrollState()
     ASSERT(document);
 
     if (m_currentItem->isCurrentDocument(document) && document->isActive()) {
-        LOG(Loading, "WebCoreLoading %s: saving form state to %p", m_frame->tree()->uniqueName().string().utf8().data(), m_currentItem.get());
+        LOG(Loading, "WebCoreLoading %s: saving form state to %p", m_frame->tree().uniqueName().string().utf8().data(), m_currentItem.get());
         m_currentItem->setDocumentState(document->formElementsState());
     }
 
@@ -145,7 +145,7 @@ bool HistoryController::shouldStopLoadingForHistoryItem(HistoryItem* targetItem)
 // This includes recursion to handle loading into framesets properly
 void HistoryController::goToItem(HistoryItem* targetItem)
 {
-    ASSERT(!m_frame->tree()->parent());
+    ASSERT(!m_frame->tree().parent());
 
     // shouldGoToHistoryItem is a private delegate method. This is needed to fix:
     // <rdar://problem/3951283> can view pages from the back/forward cache that should be disallowed by Parental Controls
@@ -181,7 +181,7 @@ void HistoryController::setDefersLoading(bool defer)
 
 void HistoryController::clearProvisionalItemsInAllFrames()
 {
-    for (RefPtr<Frame> frame = m_frame->page()->mainFrame(); frame; frame = frame->tree()->traverseNext())
+    for (RefPtr<Frame> frame = m_frame->page()->mainFrame(); frame; frame = frame->tree().traverseNext())
         frame->loader()->history()->m_provisionalItem = 0;
 }
 
@@ -198,7 +198,7 @@ void HistoryController::updateForStandardLoad()
 
 void HistoryController::updateForInitialLoadInChildFrame()
 {
-    Frame* parentFrame = m_frame->tree()->parent();
+    Frame* parentFrame = m_frame->tree().parent();
     if (parentFrame && parentFrame->loader()->history()->m_currentItem)
         parentFrame->loader()->history()->m_currentItem->setChildItem(createItem());
 }
@@ -263,7 +263,7 @@ void HistoryController::recursiveUpdateForCommit()
     }
 
     // Iterate over the rest of the tree
-    for (Frame* child = m_frame->tree()->firstChild(); child; child = child->tree()->nextSibling())
+    for (Frame* child = m_frame->tree().firstChild(); child; child = child->tree().nextSibling())
         child->loader()->history()->recursiveUpdateForCommit();
 }
 
@@ -300,7 +300,7 @@ void HistoryController::recursiveUpdateForSameDocumentNavigation()
     m_provisionalItem = 0;
 
     // Iterate over the rest of the tree.
-    for (Frame* child = m_frame->tree()->firstChild(); child; child = child->tree()->nextSibling())
+    for (Frame* child = m_frame->tree().firstChild(); child; child = child->tree().nextSibling())
         child->loader()->history()->recursiveUpdateForSameDocumentNavigation();
 }
 
@@ -352,11 +352,11 @@ void HistoryController::initializeItem(HistoryItem* item)
     if (originalURL.isEmpty())
         originalURL = blankURL();
 
-    Frame* parentFrame = m_frame->tree()->parent();
-    String parent = parentFrame ? parentFrame->tree()->uniqueName() : "";
+    Frame* parentFrame = m_frame->tree().parent();
+    String parent = parentFrame ? parentFrame->tree().uniqueName() : "";
 
     item->setURL(url);
-    item->setTarget(m_frame->tree()->uniqueName());
+    item->setTarget(m_frame->tree().uniqueName());
     item->setOriginalURLString(originalURL.string());
 
     // Save form state if this is a POST
@@ -390,7 +390,7 @@ PassRefPtr<HistoryItem> HistoryController::createItemTree(Frame* targetFrame, bo
             bfItem->setDocumentSequenceNumber(m_previousItem->documentSequenceNumber());
         }
 
-        for (Frame* child = m_frame->tree()->firstChild(); child; child = child->tree()->nextSibling()) {
+        for (Frame* child = m_frame->tree().firstChild(); child; child = child->tree().nextSibling()) {
             // If the child is a frame corresponding to an <object> element that never loaded,
             // we don't want to create a history item, because that causes fallback content
             // to be ignored on reload.
@@ -422,7 +422,7 @@ void HistoryController::recursiveSetProvisionalItem(HistoryItem* item, HistoryIt
             String childFrameName = childItems[i]->target();
             HistoryItem* fromChildItem = fromItem->childItemWithTarget(childFrameName);
             ASSERT(fromChildItem);
-            Frame* childFrame = m_frame->tree()->child(childFrameName);
+            Frame* childFrame = m_frame->tree().child(childFrameName);
             ASSERT(childFrame);
             childFrame->loader()->history()->recursiveSetProvisionalItem(childItems[i].get(), fromChildItem);
         }
@@ -444,7 +444,7 @@ void HistoryController::recursiveGoToItem(HistoryItem* item, HistoryItem* fromIt
             String childFrameName = childItems[i]->target();
             HistoryItem* fromChildItem = fromItem->childItemWithTarget(childFrameName);
             ASSERT(fromChildItem);
-            Frame* childFrame = m_frame->tree()->child(childFrameName);
+            Frame* childFrame = m_frame->tree().child(childFrameName);
             ASSERT(childFrame);
             childFrame->loader()->history()->recursiveGoToItem(childItems[i].get(), fromChildItem);
         }
@@ -473,16 +473,16 @@ bool HistoryController::itemsAreClones(HistoryItem* item1, HistoryItem* item2) c
 // Helper method that determines whether the current frame tree matches given history item's.
 bool HistoryController::currentFramesMatchItem(HistoryItem* item) const
 {
-    if ((!m_frame->tree()->uniqueName().isEmpty() || !item->target().isEmpty()) && m_frame->tree()->uniqueName() != item->target())
+    if ((!m_frame->tree().uniqueName().isEmpty() || !item->target().isEmpty()) && m_frame->tree().uniqueName() != item->target())
         return false;
 
     const HistoryItemVector& childItems = item->children();
-    if (childItems.size() != m_frame->tree()->childCount())
+    if (childItems.size() != m_frame->tree().childCount())
         return false;
 
     unsigned size = childItems.size();
     for (unsigned i = 0; i < size; ++i) {
-        if (!m_frame->tree()->child(childItems[i]->target()))
+        if (!m_frame->tree().child(childItems[i]->target()))
             return false;
     }