Move some AX attrs from AXNodeData to AXTreeData.

ui/accessibility/ax_tree_source.h

Index: ui/accessibility/ax_tree_source.h
diff --git a/ui/accessibility/ax_tree_source.h b/ui/accessibility/ax_tree_source.h
index fe6a8280f4d5eadf70b8553e5a07b35356f87940..ae9f8cab2071457e7213b19df05e3262ef197f02 100644
--- a/ui/accessibility/ax_tree_source.h
+++ b/ui/accessibility/ax_tree_source.h
@@ -17,11 +17,14 @@ namespace ui {
 // as an AXNodeData. This is the primary interface to use when
 // an accessibility tree will be sent over an IPC before being
 // consumed.
-template<typename AXNodeSource, typename AXNodeData>
+template<typename AXNodeSource, typename AXNodeData, typename AXTreeData>
 class AXTreeSource {
  public:
   virtual ~AXTreeSource() {}
 
+  // Get the tree data.
+  virtual AXTreeData GetTreeData() const = 0;
+
   // Get the root of the tree.
   virtual AXNodeSource GetRoot() const = 0;