First step to move common accessibility code out of content.

ui/accessibility/ax_serializable_tree.cc

Index: ui/accessibility/ax_serializable_tree.cc
diff --git a/ui/accessibility/ax_serializable_tree.cc b/ui/accessibility/ax_serializable_tree.cc
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index 0000000000000000000000000000000000000000..ab63f552607f65af129c11d7cfc9163eccaf4d17
--- /dev/null
+++ b/ui/accessibility/ax_serializable_tree.cc
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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.
+
+#include "ui/accessibility/ax_serializable_tree.h"
+
+#include "ui/accessibility/ax_node.h"
+
+namespace ui {
+
+// This class is an implementation of the AXTreeSource interface with
+// AXNode as the node type, that just delegates to an AXTree. The purpose
+// of this is so that AXTreeSerializer only needs to work with the
+// AXTreeSource abstraction and doesn't need to actually know about
+// AXTree directly. Another AXTreeSource is used to abstract the Blink
+// accessibility tree.
+class AX_EXPORT AXTreeSourceAdapter : public AXTreeSource<AXNode> {
+ public:
+  AXTreeSourceAdapter(AXTree* tree) : tree_(tree) {}
+  virtual ~AXTreeSourceAdapter() {}
+
+  // AXTreeSource implementation.
+  virtual AXNode* GetFromId(int32 id) const OVERRIDE {
+    return tree_->GetFromId(id);
+  }
+
+  virtual int32 GetId(const AXNode* node) const OVERRIDE {
+    return node->id();
+  }
+
+  virtual int GetChildCount(const AXNode* node) const OVERRIDE {
+    return node->child_count();
+  }
+
+  virtual AXNode* GetChildAtIndex(const AXNode* node, int index)
+      const OVERRIDE {
+    return node->ChildAtIndex(index);
+  }
+
+  virtual int32 GetParentId(const AXNode* node) const OVERRIDE {
+    if (node->parent())
+      return node->parent()->id();
+    else
+      return 0;
+  }
+
+  virtual void SerializeNode(
+      const AXNode* node, AXNodeData* out_data) const OVERRIDE {
+    *out_data = node->data();
+  }
+
+ private:
+  AXTree* tree_;
+};
+
+AXSerializableTree::AXSerializableTree()
+    : AXTree() {}
+
+AXSerializableTree::AXSerializableTree(const AXTreeUpdate& initial_state)
+    : AXTree(initial_state) {
+}
+
+AXSerializableTree::~AXSerializableTree() {
+}
+
+AXTreeSource<AXNode>* AXSerializableTree::CreateTreeSource() {
+  return new AXTreeSourceAdapter(this);
+}
+
+}  // namespace ui