Remove internal uses of mojo::Array and mojo::WTFArray.

mojo/public/cpp/bindings/native_struct.h

 // Copyright 2016 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_NATIVE_STRUCT_H_
 #define MOJO_PUBLIC_CPP_BINDINGS_NATIVE_STRUCT_H_
 
-#include "mojo/public/cpp/bindings/array.h"
+#include <vector>
+
+#include "base/optional.h"
 #include "mojo/public/cpp/bindings/bindings_export.h"
 #include "mojo/public/cpp/bindings/lib/native_struct_data.h"
 #include "mojo/public/cpp/bindings/struct_ptr.h"
 #include "mojo/public/cpp/bindings/type_converter.h"
 
 namespace mojo {
 
 class NativeStruct;
 using NativeStructPtr = StructPtr<NativeStruct>;
 
@@ skipping 15 matching lines @@
     return TypeConverter<U, NativeStruct>::Convert(*this);
   }
 
   NativeStruct();
   ~NativeStruct();
 
   NativeStructPtr Clone() const;
   bool Equals(const NativeStruct& other) const;
   size_t Hash(size_t seed) const;
 
-  Array<uint8_t> data;
+  base::Optional<std::vector<uint8_t>> data;
 };
 
 }  // namespace mojo
 
 #endif  // MOJO_PUBLIC_CPP_BINDINGS_NATIVE_STRUCT_H_