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 46729dd062e1c7ff983d93e6bd7d2b5bd8f0feaf..f14922a8dc02e6a4110e9654e71d21880ace6ea5 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() {
@@ -100,7 +100,6 @@ 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() {}