mojo: Allow circular dependencies between structs

mojo/public/cpp/bindings/struct_ptr.h

 // Copyright 2014 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #ifndef MOJO_PUBLIC_CPP_BINDINGS_STRUCT_PTR_H_
 #define MOJO_PUBLIC_CPP_BINDINGS_STRUCT_PTR_H_
 
 #include <new>
 
+#include "mojo/public/cpp/bindings/type_converter.h"
 #include "mojo/public/cpp/environment/logging.h"
 #include "mojo/public/cpp/system/macros.h"
 
 namespace mojo {
 namespace internal {
 
 template <typename Struct>
 class StructHelper {
  public:
   template <typename Ptr>
   static void Initialize(Ptr* ptr) { ptr->Initialize(); }
 };
 
 }  // namespace internal
 
 template <typename Struct>
 class StructPtr {
   MOJO_MOVE_ONLY_TYPE_FOR_CPP_03(StructPtr, RValue);
  public:
-  typedef typename Struct::Data_ Data_;
 
   StructPtr() : ptr_(nullptr) {}
   ~StructPtr() {
     delete ptr_;
   }
 
   StructPtr(RValue other) : ptr_(nullptr) { Take(other.object); }
   StructPtr& operator=(RValue other) {
     Take(other.object);
     return *this;
@@ skipping 46 matching lines @@
   }
 
   Struct* ptr_;
 };
 
 // Designed to be used when Struct is small and copyable.
 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() {}
 
   InlinedStructPtr(RValue other) : is_null_(true) { Take(other.object); }
   InlinedStructPtr& operator=(RValue other) {
     Take(other.object);
     return *this;
   }
 
@@ skipping 40 matching lines @@
     Swap(other);
   }
 
   mutable Struct value_;
   bool is_null_;
 };
 
 }  // namespace mojo
 
 #endif  // MOJO_PUBLIC_CPP_BINDINGS_STRUCT_PTR_H_