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diff --git a/accessible/base/TreeWalker.h b/accessible/base/TreeWalker.h
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+++ b/accessible/base/TreeWalker.h
@@ -0,0 +1,144 @@
+/* -*- 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/. */
+
+#ifndef mozilla_a11y_TreeWalker_h_
+#define mozilla_a11y_TreeWalker_h_
+
+#include "mozilla/Attributes.h"
+#include <stdint.h>
+#include "mozilla/dom/ChildIterator.h"
+#include "nsCOMPtr.h"
+
+class nsIContent;
+
+namespace mozilla {
+namespace a11y {
+
+class Accessible;
+class DocAccessible;
+
+/**
+ * This class is used to walk the DOM tree to create accessible tree.
+ */
+class TreeWalker final
+{
+public:
+  enum {
+    // used to walk the existing tree of the given node
+    eWalkCache = 1,
+    // used to walk the context tree starting from given node
+    eWalkContextTree = 2 | eWalkCache
+  };
+
+  /**
+   * Used to navigate and create if needed the accessible children.
+   */
+  explicit TreeWalker(Accessible* aContext);
+
+  /**
+   * Used to navigate the accessible children relative to the anchor.
+   *
+   * @param aContext [in] container accessible for the given node, used to
+   *                   define accessible context
+   * @param aAnchorNode [in] the node the search will be prepared relative to
+   * @param aFlags   [in] flags (see enum above)
+   */
+  TreeWalker(Accessible* aContext, nsIContent* aAnchorNode, uint32_t aFlags = eWalkCache);
+
+  ~TreeWalker();
+
+  /**
+   * Resets the walker state, and sets the given node as an anchor. Returns a
+   * first accessible element within the node including the node itself.
+   */
+  Accessible* Scope(nsIContent* aAnchorNode);
+
+  /**
+   * Resets the walker state.
+   */
+  void Reset()
+  {
+    mPhase = eAtStart;
+    mStateStack.Clear();
+    mARIAOwnsIdx = 0;
+  }
+
+  /**
+   * Sets the walker state to the given child node if it's within the anchor.
+   */
+  bool Seek(nsIContent* aChildNode);
+
+  /**
+   * Return the next/prev accessible.
+   *
+   * @note Returned accessible is bound to the document, if the accessible is
+   *       rejected during tree creation then the caller should be unbind it
+   *       from the document.
+   */
+  Accessible* Next();
+  Accessible* Prev();
+
+  Accessible* Context() const { return mContext; }
+  DocAccessible* Document() const { return mDoc; }
+
+private:
+  TreeWalker();
+  TreeWalker(const TreeWalker&);
+  TreeWalker& operator =(const TreeWalker&);
+
+  /**
+   * Return an accessible for the given node if any.
+   */
+  Accessible* AccessibleFor(nsIContent* aNode, uint32_t aFlags,
+                            bool* aSkipSubtree);
+
+  /**
+   * Create new state for the given node and push it on top of stack / at bottom
+   * of stack.
+   *
+   * @note State stack is used to navigate up/down the DOM subtree during
+   *        accessible children search.
+   */
+  dom::AllChildrenIterator* PushState(nsIContent* aContent,
+                                      bool aStartAtBeginning)
+  {
+    return mStateStack.AppendElement(
+      dom::AllChildrenIterator(aContent, mChildFilter, aStartAtBeginning));
+  }
+  dom::AllChildrenIterator* PrependState(nsIContent* aContent,
+                                         bool aStartAtBeginning)
+  {
+    return mStateStack.InsertElementAt(0,
+      dom::AllChildrenIterator(aContent, mChildFilter, aStartAtBeginning));
+  }
+
+  /**
+   * Pop state from stack.
+   */
+  dom::AllChildrenIterator* PopState();
+
+  DocAccessible* mDoc;
+  Accessible* mContext;
+  nsIContent* mAnchorNode;
+
+  AutoTArray<dom::AllChildrenIterator, 20> mStateStack;
+  uint32_t mARIAOwnsIdx;
+
+  int32_t mChildFilter;
+  uint32_t mFlags;
+
+  enum Phase {
+    eAtStart,
+    eAtDOM,
+    eAtARIAOwns,
+    eAtEnd
+  };
+  Phase mPhase;
+};
+
+} // namespace a11y
+} // namespace mozilla
+
+#endif // mozilla_a11y_TreeWalker_h_