PaymentHandler: Implement PaymentInstruments.delete().

content/browser/payments/payment_manager.h

Index: content/browser/payments/payment_manager.h
diff --git a/content/browser/payments/payment_manager.h b/content/browser/payments/payment_manager.h
index 772b25d799012989fd4158d833782078c9c974a6..4a115e25829dba0037356a37757a7c1848a77533 100644
--- a/content/browser/payments/payment_manager.h
+++ b/content/browser/payments/payment_manager.h
@@ -36,12 +36,15 @@ class CONTENT_EXPORT PaymentManager
   void SetManifest(payments::mojom::PaymentAppManifestPtr manifest,
                    const SetManifestCallback& callback) override;
   void GetManifest(const GetManifestCallback& callback) override;
+  void DeletePaymentInstrument(
+      const std::string& instrument_key,
+      const DeletePaymentInstrumentCallback& callback) override;
   void SetPaymentInstrument(
-      const std::string& instrumentKey,
+      const std::string& instrument_key,
       payments::mojom::PaymentInstrumentPtr details,
       const SetPaymentInstrumentCallback& callback) override;
   void GetPaymentInstrument(
-      const std::string& instrumentKey,
+      const std::string& instrument_key,
       const GetPaymentInstrumentCallback& callback) override;
 
   // Called when an error is detected on binding_.