PaymentHandler: Implement PaymentInstruments.delete().

components/payments/mojom/payment_app.mojom

Index: components/payments/mojom/payment_app.mojom
diff --git a/components/payments/mojom/payment_app.mojom b/components/payments/mojom/payment_app.mojom
index 5cc4e3bca4ea82398d46887aada18e412b7d4cb5..8a36101e553af49af5b82d06e60e57ffc8f331b4 100644
--- a/components/payments/mojom/payment_app.mojom
+++ b/components/payments/mojom/payment_app.mojom
@@ -48,6 +48,8 @@ interface PaymentManager {
       => (PaymentAppManifestError error);
   GetManifest()
       => (PaymentAppManifest payment_app_manifest, PaymentAppManifestError error);
+  DeletePaymentInstrument(string instrumentKey)

[please use gerrit instead, 2017/04/25 15:21:40]

Let's use under_score_variable_names everywhere in the file.

[zino, 2017/04/25 21:48:51]

Done.

I have to modify 61 line and 64 line but the change requires service worker
part.
Then, I will have to add a reviewer in this CL. So, I'll fix it in separated CL.

[zino, 2017/04/25 21:59:02]

I uploaded separated CL.

https://codereview.chromium.org/2839813005

+      => (PaymentHandlerStatus status);
   SetPaymentInstrument(string instrumentKey, PaymentInstrument instrument)
       => (PaymentHandlerStatus status);
   GetPaymentInstrument(string instrumentKey)