Add base::UnguessableToken

mojo/common/common_custom_types_struct_traits.h

Index: mojo/common/common_custom_types_struct_traits.h
diff --git a/mojo/common/common_custom_types_struct_traits.h b/mojo/common/common_custom_types_struct_traits.h
index 37fc5ca298a024430ca3d4e61c437d766a9749ea..706aef2428bb1942e9b43c54a78caf9caeaff2c8 100644
--- a/mojo/common/common_custom_types_struct_traits.h
+++ b/mojo/common/common_custom_types_struct_traits.h
@@ -5,6 +5,7 @@
 #ifndef MOJO_COMMON_COMMON_CUSTOM_TYPES_STRUCT_TRAITS_H_
 #define MOJO_COMMON_COMMON_CUSTOM_TYPES_STRUCT_TRAITS_H_
 
+#include "base/nonce.h"
 #include "base/version.h"
 #include "mojo/common/common_custom_types.mojom-shared.h"
 
@@ -23,6 +24,22 @@ struct StructTraits<mojo::common::mojom::VersionDataView, base::Version> {
                    base::Version* out);
 };
 
+template <>
+struct StructTraits<mojo::common::mojom::NonceDataView, base::Nonce> {
+  static bool IsNull(const base::Nonce& nonce) { return nonce.is_empty(); }
+
+  static void SetToNull(base::Nonce* out) { *out = base::Nonce(); }
+
+  static uint64_t high(const base::Nonce& nonce) { return nonce.high(); }
+
+  static uint64_t low(const base::Nonce& nonce) { return nonce.low(); }
+
+  static bool Read(mojo::common::mojom::NonceDataView data, base::Nonce* out) {
+    *out = base::Nonce::Deserialize(data.high(), data.low());
+    return !out->is_empty();
+  }
+};
+
 }  // namespace mojo
 
 #endif  // MOJO_COMMON_COMMON_CUSTOM_TYPES_STRUCT_TRAITS_H_