Add base::UnguessableToken

mojo/common/common_custom_types.mojom

Index: mojo/common/common_custom_types.mojom
diff --git a/mojo/common/common_custom_types.mojom b/mojo/common/common_custom_types.mojom
index 1eca3a5a6f5ccba3d96b5aea3e28aedda7edb6f4..66fea215862fbf1680e4db17bab39bf830b1f5ff 100644
--- a/mojo/common/common_custom_types.mojom
+++ b/mojo/common/common_custom_types.mojom
@@ -14,6 +14,9 @@ struct ListValue;
 struct DictionaryValue;
 
 [Native]
+struct Nonce;

[Fady Samuel, 2016/09/13 17:45:00]

Sorry just noticed. Could we please make this not [Native]? Could you please
define the high and low here and write StructTraits? Thanks!

[tguilbert, 2016/09/13 20:20:19]

Done.

I originally had StructTraits but encountered huge linking errors in the
component build, so I switched to [Native].

From looking around, it seems like a lot of the StructTraits have their
implementation in the .h file (url_gurl_struct_traits.h for instance). Is this
the proper way to go?

[Fady Samuel, 2016/09/13 20:28:44]

That's fine. If you want some of the StructTraits to live in a cc file you have
to specify it in the typemap:

https://cs.chromium.org/chromium/src/cc/ipc/compositor_frame.typemap

[tguilbert, 2016/09/13 21:11:44]

Ok, thanks for the info.

+
+[Native]
 struct Time;
 
 [Native]