diff -r 000000000000 -r 6474c204b198 docshell/base/nsDocShellEnumerator.cpp
--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/docshell/base/nsDocShellEnumerator.cpp	Wed Dec 31 06:09:35 2014 +0100
@@ -0,0 +1,179 @@
+/* -*- Mode: C++; tab-width: 2; indent-tabs-mode: nil; c-basic-offset: 2 -*-
+ *
+ * This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+
+#include "nsDocShellEnumerator.h"
+
+#include "nsIDocShellTreeItem.h"
+
+nsDocShellEnumerator::nsDocShellEnumerator(int32_t inEnumerationDirection)
+: mRootItem(nullptr)
+, mCurIndex(0)
+, mDocShellType(nsIDocShellTreeItem::typeAll)
+, mArrayValid(false)
+, mEnumerationDirection(inEnumerationDirection)
+{
+}
+
+nsDocShellEnumerator::~nsDocShellEnumerator()
+{
+}
+
+NS_IMPL_ISUPPORTS(nsDocShellEnumerator, nsISimpleEnumerator)
+
+
+/* nsISupports getNext (); */
+NS_IMETHODIMP nsDocShellEnumerator::GetNext(nsISupports **outCurItem)
+{
+  NS_ENSURE_ARG_POINTER(outCurItem);
+  *outCurItem = nullptr;
+  
+  nsresult rv = EnsureDocShellArray();
+  if (NS_FAILED(rv)) return rv;
+  
+  if (mCurIndex >= mItemArray.Length()) {
+    return NS_ERROR_FAILURE;
+  }
+
+  // post-increment is important here
+  nsCOMPtr<nsISupports> item = do_QueryReferent(mItemArray[mCurIndex++], &rv);
+  item.forget(outCurItem);
+  return rv;
+}
+
+/* boolean hasMoreElements (); */
+NS_IMETHODIMP nsDocShellEnumerator::HasMoreElements(bool *outHasMore)
+{
+  NS_ENSURE_ARG_POINTER(outHasMore);
+  *outHasMore = false;
+
+  nsresult rv = EnsureDocShellArray();
+  if (NS_FAILED(rv)) return rv;
+
+  *outHasMore = (mCurIndex < mItemArray.Length());
+  return NS_OK;
+}
+
+nsresult nsDocShellEnumerator::GetEnumerationRootItem(nsIDocShellTreeItem * *aEnumerationRootItem)
+{
+  NS_ENSURE_ARG_POINTER(aEnumerationRootItem);
+  nsCOMPtr<nsIDocShellTreeItem> item = do_QueryReferent(mRootItem);
+  item.forget(aEnumerationRootItem);
+  return NS_OK;
+}
+
+nsresult nsDocShellEnumerator::SetEnumerationRootItem(nsIDocShellTreeItem * aEnumerationRootItem)
+{
+  mRootItem = do_GetWeakReference(aEnumerationRootItem);
+  ClearState();
+  return NS_OK;
+}
+
+nsresult nsDocShellEnumerator::GetEnumDocShellType(int32_t *aEnumerationItemType)
+{
+  NS_ENSURE_ARG_POINTER(aEnumerationItemType);
+  *aEnumerationItemType = mDocShellType;
+  return NS_OK;
+}
+
+nsresult nsDocShellEnumerator::SetEnumDocShellType(int32_t aEnumerationItemType)
+{
+  mDocShellType = aEnumerationItemType;
+  ClearState();
+  return NS_OK;
+}
+
+nsresult nsDocShellEnumerator::First()
+{
+  mCurIndex = 0;
+  return EnsureDocShellArray();
+}
+
+nsresult nsDocShellEnumerator::EnsureDocShellArray()
+{
+  if (!mArrayValid)
+  {
+    mArrayValid = true;
+    return BuildDocShellArray(mItemArray);
+  }
+  
+  return NS_OK;
+}
+
+nsresult nsDocShellEnumerator::ClearState()
+{
+  mItemArray.Clear();
+  mArrayValid = false;
+  mCurIndex = 0;
+  return NS_OK;
+}
+
+nsresult nsDocShellEnumerator::BuildDocShellArray(nsTArray<nsWeakPtr>& inItemArray)
+{
+  NS_ENSURE_TRUE(mRootItem, NS_ERROR_NOT_INITIALIZED);
+  inItemArray.Clear();
+  nsCOMPtr<nsIDocShellTreeItem> item = do_QueryReferent(mRootItem);
+  return BuildArrayRecursive(item, inItemArray);
+}
+
+nsresult nsDocShellForwardsEnumerator::BuildArrayRecursive(nsIDocShellTreeItem* inItem, nsTArray<nsWeakPtr>& inItemArray)
+{
+  nsresult rv;
+
+  // add this item to the array
+  if (mDocShellType == nsIDocShellTreeItem::typeAll ||
+      inItem->ItemType() == mDocShellType) {
+    nsWeakPtr weakItem = do_GetWeakReference(inItem);
+    if (!inItemArray.AppendElement(weakItem))
+      return NS_ERROR_OUT_OF_MEMORY;
+  }
+
+  int32_t   numChildren;
+  rv = inItem->GetChildCount(&numChildren);
+  if (NS_FAILED(rv)) return rv;
+  
+  for (int32_t i = 0; i < numChildren; ++i)
+  {
+    nsCOMPtr<nsIDocShellTreeItem> curChild;
+    rv = inItem->GetChildAt(i, getter_AddRefs(curChild));
+    if (NS_FAILED(rv)) return rv;
+      
+    rv = BuildArrayRecursive(curChild, inItemArray);
+    if (NS_FAILED(rv)) return rv;
+  }
+
+  return NS_OK;
+}
+
+
+nsresult nsDocShellBackwardsEnumerator::BuildArrayRecursive(nsIDocShellTreeItem* inItem, nsTArray<nsWeakPtr>& inItemArray)
+{
+  nsresult rv;
+
+  int32_t   numChildren;
+  rv = inItem->GetChildCount(&numChildren);
+  if (NS_FAILED(rv)) return rv;
+  
+  for (int32_t i = numChildren - 1; i >= 0; --i)
+  {
+    nsCOMPtr<nsIDocShellTreeItem> curChild;
+    rv = inItem->GetChildAt(i, getter_AddRefs(curChild));
+    if (NS_FAILED(rv)) return rv;
+      
+    rv = BuildArrayRecursive(curChild, inItemArray);
+    if (NS_FAILED(rv)) return rv;
+  }
+
+  // add this item to the array
+  if (mDocShellType == nsIDocShellTreeItem::typeAll ||
+      inItem->ItemType() == mDocShellType) {
+    nsWeakPtr weakItem = do_GetWeakReference(inItem);
+    if (!inItemArray.AppendElement(weakItem))
+      return NS_ERROR_OUT_OF_MEMORY;
+  }
+
+  return NS_OK;
+}