First step to move common accessibility code out of content.

content/common/ax_node_impl.h

Index: content/common/ax_node_impl.h
diff --git a/content/common/ax_node_impl.h b/content/common/ax_node_impl.h
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+++ b/content/common/ax_node_impl.h
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+// Copyright (c) 2013 The Chromium Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style license that can be
+// found in the LICENSE file.
+
+#ifndef CONTENT_COMMON_AX_NODE_IMPL_H_
+#define CONTENT_COMMON_AX_NODE_IMPL_H_
+
+#include "content/public/common/ax_node.h"
+#include "content/public/common/ax_node_data.h"
+
+namespace content {
+
+class CONTENT_EXPORT AXNodeImpl : public AXNode {
+ public:
+  AXNodeImpl();
+  virtual ~AXNodeImpl();
+
+  // AXNode implementation.
+  virtual int32 GetId() const OVERRIDE;
+  virtual AXNode* GetParent() const OVERRIDE;
+  virtual int GetChildCount() const OVERRIDE;
+  virtual AXNode* ChildAtIndex(int index) const OVERRIDE;
+  virtual const AXNodeData& data() const OVERRIDE;
+
+  const std::vector<AXNodeImpl*>& children() const { return children_; }
+
+  // Initialize the node. This sets up its place in the tree but does
+  // not set its data yet. After initialization, only index_in_parent
+  // is allowed to change, the others are guaranteed to never change.
+  virtual void Init(AXNodeImpl* parent, int32 id, int32 index_in_parent);
+
+  // Set the node's accessibility data. This may be done during initial
+  // initialization or later when the node data changes.
+  virtual void SetData(const AXNodeData& src);
+
+  // Update the index in parent if siblings were inserted or deleted.
+  void UpdateIndexInParent(int index_in_parent);
+
+  // Swap the internal children vector with |children|. This instance
+  // now owns all of the passed children.
+  virtual void SwapChildren(std::vector<AXNodeImpl*>& children);
+
+  // This is called when the AXTree no longer includes this node in the
+  // tree. Reference counting is used on some platforms because the
+  // operating system may hold onto a reference to an AXNode
+  // object even after we're through with it, so this may decrement the
+  // reference count and clear out the object's data.
+  virtual void Destroy();
+
+ private:
+  int index_in_parent_;
+  AXNodeImpl* parent_;
+  std::vector<AXNodeImpl*> children_;
+  AXNodeData data_;
+};
+
+
+}  // namespace content
+
+#endif  // CONTENT_COMMON_AX_NODE_IMPL_H_