Update mojo sdk to rev 9fbbc4f0fef1187312316c0ed992342474e139f1

mojo/public/cpp/bindings/lib/union_accessor.h

+// Copyright 2015 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_LIB_UNION_ACCESSOR_H_
+#define MOJO_PUBLIC_CPP_BINDINGS_LIB_UNION_ACCESSOR_H_
+
+namespace mojo {
+namespace internal {
+
+// When serializing and deserializing Unions, it is necessary to access
+// the private fields and methods of the Union. This allows us to do that
+// without leaking those same fields and methods in the Union interface.
+// All Union wrappers are friends of this class allowing such access.
+template <typename U>
+class UnionAccessor {
+ public:
+  explicit UnionAccessor(U* u) : u_(u) {}
+
+  typename U::Union_* data() { return &(u_->data_); }
+
+  typename U::Tag* tag() { return &(u_->tag_); }
+
+  void SwitchActive(typename U::Tag new_tag) { u_->SwitchActive(new_tag); }
+
+ private:
+  U* u_;
+};
+
+}  // namespace internal
+}  // namespace mojo
+
+#endif  // MOJO_PUBLIC_CPP_BINDINGS_LIB_UNION_ACCESSOR_H_