Mojo: Align string sizes when serializing a native type.

mojo/public/cpp/bindings/tests/struct_with_traits_impl_traits.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_TESTS_STRUCT_WITH_TRAITS_IMPL_TRAITS_H_
 #define MOJO_PUBLIC_CPP_BINDINGS_TESTS_STRUCT_WITH_TRAITS_IMPL_TRAITS_H_
 
 #include <stdint.h>
 
 #include <string>
@@ skipping 20 matching lines @@
     return value.get_uint32();
   }
 
   static uint64_t f_uint64(const test::StructWithTraitsImpl& value) {
     return value.get_uint64();
   }
 
   static base::StringPiece f_string(const test::StructWithTraitsImpl& value) {
     return value.get_string();
   }
+
+  static base::StringPiece f_string2(const test::StructWithTraitsImpl& value) {
+    return value.get_string();
+  }
 };
 
 }  // namespace mojo
 
 #endif  // MOJO_PUBLIC_CPP_BINDINGS_TESTS_STRUCT_WITH_TRAITS_IMPL_TRAITS_H_