First step to move common accessibility code out of content.

content/common/ax_tree_serializer.cc

Index: content/common/ax_tree_serializer.cc
diff --git a/tools/gn/script_values.cc b/content/common/ax_tree_serializer.cc
similarity index 51%
copy from tools/gn/script_values.cc
copy to content/common/ax_tree_serializer.cc
index c5d7989f3f192e343c465a1b9e4c659fc475a6aa..6c513b4947ce1deb05399a18dca216a9c5b8632f 100644
--- a/tools/gn/script_values.cc
+++ b/content/common/ax_tree_serializer.cc
@@ -2,10 +2,14 @@
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
-#include "tools/gn/script_values.h"
+#include "content/common/ax_tree_serializer.h"
 
-ScriptValues::ScriptValues() {
+namespace content {
+
+ClientTreeNode::ClientTreeNode() {
 }
 
-ScriptValues::~ScriptValues() {
+ClientTreeNode::~ClientTreeNode() {
 }
+
+}  // namespace content