Add base::UnguessableToken << operator

base/unguessable_token.h

Index: base/unguessable_token.h
diff --git a/base/unguessable_token.h b/base/unguessable_token.h
index 64b1868886f2f0d06c613efa79a1f84ceb7b3c59..07dd67fcfcb681573320aaa5573e180f870acb14 100644
--- a/base/unguessable_token.h
+++ b/base/unguessable_token.h
@@ -7,6 +7,7 @@
 
 #include <stdint.h>
 #include <string.h>
+#include <iosfwd>
 #include <tuple>
 
 #include "base/base_export.h"
@@ -94,6 +95,9 @@ struct UnguessableTokenHash {
   }
 };
 
+BASE_EXPORT std::ostream& operator<<(std::ostream& out,

[danakj, 2016/09/20 00:07:08]

nit: order this beside (after) the class, before the hash struct

[tguilbert, 2016/09/20 00:50:34]

Done.

+                                     const UnguessableToken& token);
+
 }  // namespace base
 
 #endif  // BASE_UNGUESSABLE_TOKEN_H_