[Web Payments] Implement the CVC Unmask dialog.

components/payments/content/payment_request_delegate.h

Index: components/payments/content/payment_request_delegate.h
diff --git a/components/payments/content/payment_request_delegate.h b/components/payments/content/payment_request_delegate.h
index dc421cdb4bc65b6ba98509511b59634299215fc4..f6e227eeb0f9b3360bf207fb7dfcfc7c91b57284 100644
--- a/components/payments/content/payment_request_delegate.h
+++ b/components/payments/content/payment_request_delegate.h
@@ -7,6 +7,11 @@
 
 #include <string>
 
+#include "base/memory/weak_ptr.h"
+#include "components/autofill/core/browser/autofill_client.h"
+#include "components/autofill/core/browser/payments/full_card_request.h"
+#include "components/payments/core/autofill_payment_instrument.h"
+
 namespace autofill {
 class PersonalDataManager;
 }
@@ -15,7 +20,8 @@ namespace payments {
 
 class PaymentRequest;
 
-class PaymentRequestDelegate {
+class PaymentRequestDelegate
+    : public AutofillPaymentInstrument::FullCardRequestDelegate {
  public:
   virtual ~PaymentRequestDelegate() {}