Refactor content/ to use ui::AXNodeData instead of blink.

ui/accessibility/ax_tree.h

Index: ui/accessibility/ax_tree.h
diff --git a/ui/accessibility/ax_tree.h b/ui/accessibility/ax_tree.h
index 773a773adf548da10b2940d7ecaec3d35edccc71..0241d3e1aaa1ca3954adac3f1c3e1888ca95fe6b 100644
--- a/ui/accessibility/ax_tree.h
+++ b/ui/accessibility/ax_tree.h
@@ -35,6 +35,9 @@ class AX_EXPORT AXTree {
   // should not be trusted any longer.
   virtual bool Unserialize(const AXTreeUpdate& update);
 
+  // Return a multi-line indented string representation, for logging.
+  std::string ToString() const;
+
   // A string describing the error from an unsuccessful Unserialize,
   // for testing and debugging.
   const std::string& error() { return error_; }