mojo: Allow circular dependencies between structs

mojo/public/cpp/bindings/struct_ptr.h

Index: mojo/public/cpp/bindings/struct_ptr.h
diff --git a/mojo/public/cpp/bindings/struct_ptr.h b/mojo/public/cpp/bindings/struct_ptr.h
index 58b6cec87f9c1d96d1ed9101eac7835c70a22f4d..553f481045d713f2598916794851fd1acea2ebf8 100644
--- a/mojo/public/cpp/bindings/struct_ptr.h
+++ b/mojo/public/cpp/bindings/struct_ptr.h
@@ -7,6 +7,7 @@
 
 #include <new>
 
+#include "mojo/public/cpp/bindings/type_converter.h"
 #include "mojo/public/cpp/environment/logging.h"
 #include "mojo/public/cpp/system/macros.h"
 
@@ -26,7 +27,6 @@ template <typename Struct>
 class StructPtr {
   MOJO_MOVE_ONLY_TYPE_FOR_CPP_03(StructPtr, RValue);
  public:
-  typedef typename Struct::Data_ Data_;
 
   StructPtr() : ptr_(nullptr) {}
   ~StructPtr() {
@@ -93,7 +93,6 @@ template <typename Struct>
 class InlinedStructPtr {
   MOJO_MOVE_ONLY_TYPE_FOR_CPP_03(InlinedStructPtr, RValue);
  public:
-  typedef typename Struct::Data_ Data_;
 
   InlinedStructPtr() : is_null_(true) {}
   ~InlinedStructPtr() {}