Add a regression test for the CardUnmaskPrompt.

components/autofill/core/browser/autofill_test_utils.h

Index: components/autofill/core/browser/autofill_test_utils.h
diff --git a/components/autofill/core/browser/autofill_test_utils.h b/components/autofill/core/browser/autofill_test_utils.h
index 213d336e6ea09ef4ea25204d0dddd31b4ce62e15..466e1a112ad844d3d91733dea9e02294e9ea85dc 100644
--- a/components/autofill/core/browser/autofill_test_utils.h
+++ b/components/autofill/core/browser/autofill_test_utils.h
@@ -69,6 +69,9 @@ CreditCard GetVerifiedCreditCard();
 // Returns a verified credit card full of dummy info, different to the above.
 CreditCard GetVerifiedCreditCard2();
 
+// Returns a masked server card full of dummy info.
+CreditCard GetMaskedServerCard();
+
 // A unit testing utility that is common to a number of the Autofill unit
 // tests.  |SetProfileInfo| provides a quick way to populate a profile with
 // c-strings.