Add base::UnguessableToken

mojo/common/common_custom_types_struct_traits.cc

Index: mojo/common/common_custom_types_struct_traits.cc
diff --git a/mojo/common/common_custom_types_struct_traits.cc b/mojo/common/common_custom_types_struct_traits.cc
index 91fc9524d2b3b14a4ef788c7f6dc8f03e0db1947..21026d4d78e9ce3d6486d4435d9b74f3057ae05c 100644
--- a/mojo/common/common_custom_types_struct_traits.cc
+++ b/mojo/common/common_custom_types_struct_traits.cc
@@ -27,4 +27,20 @@ bool StructTraits<mojo::common::mojom::VersionDataView, base::Version>::Read(
   return out->IsValid();
 }
 
+// static
+bool StructTraits<mojo::common::mojom::UnguessableTokenDataView,
+                  base::UnguessableToken>::
+    Read(mojo::common::mojom::UnguessableTokenDataView data,
+         base::UnguessableToken* out) {
+  uint64_t high = data.high();
+  uint64_t low = data.low();
+
+  // Receiving a zeroed UnguessableToken is a security issue.
+  if (high == 0 && low == 0)
+    return false;
+
+  *out = base::UnguessableToken::Deserialize(high, low);
+  return true;
+}
+
 }  // namespace mojo