Add base::UnguessableToken

mojo/common/common_custom_types.typemap

Index: mojo/common/common_custom_types.typemap
diff --git a/mojo/common/common_custom_types.typemap b/mojo/common/common_custom_types.typemap
index 46ee53f7718c5b08b456e42c9873e8b5d6773f92..ecd09e87be1ba6a7317dc416ec1dfa1c7d4a8b64 100644
--- a/mojo/common/common_custom_types.typemap
+++ b/mojo/common/common_custom_types.typemap
@@ -7,6 +7,7 @@ public_headers = [
   "//base/files/file_path.h",
   "//base/strings/string16.h",
   "//base/time/time.h",
+  "//base/unguessable_token.h",
   "//base/values.h",
   "//base/version.h",
 ]
@@ -14,17 +15,16 @@ traits_headers = [
   "//ipc/ipc_message_utils.h",
   "//mojo/common/common_custom_types_struct_traits.h",
 ]
-sources = [
-  "//mojo/common:struct_traits",
-]
 public_deps = [
   "//ipc",
+  "//mojo/common:struct_traits",
 ]
 
 type_mappings = [
   "mojo.common.mojom.FilePath=base::FilePath",
   "mojo.common.mojom.DictionaryValue=base::DictionaryValue",
   "mojo.common.mojom.ListValue=base::ListValue",
+  "mojo.common.mojom.UnguessableToken=base::UnguessableToken",
   "mojo.common.mojom.String16=base::string16",
   "mojo.common.mojom.Time=base::Time[copyable_pass_by_value]",
   "mojo.common.mojom.TimeDelta=base::TimeDelta[copyable_pass_by_value]",