Add canMakeActivePayment() method to web payments.

components/payments/payment_request.mojom

Index: components/payments/payment_request.mojom
diff --git a/components/payments/payment_request.mojom b/components/payments/payment_request.mojom
index 5820909d98b46c5c7153410b8d685e226a1314fc..4b4ae65858dda129886cc382e3bc49433fb9905f 100644
--- a/components/payments/payment_request.mojom
+++ b/components/payments/payment_request.mojom
@@ -77,6 +77,12 @@ enum PaymentErrorReason {
   NOT_SUPPORTED
 };
 
+enum ActivePaymentQueryResult {
+  CAN_MAKE_ACTIVE_PAYMENT,
+  CANNOT_MAKE_ACTIVE_PAYMENT,
+  QUERY_QUOTA_EXCEEDED
+};
+
 interface PaymentRequestClient {
   OnShippingAddressChange(PaymentAddress address);
   OnShippingOptionChange(string shipping_option_id);
@@ -84,6 +90,7 @@ interface PaymentRequestClient {
   OnError(PaymentErrorReason error);
   OnComplete();
   OnAbort(bool aborted_successfully);
+  OnCanMakeActivePayment(ActivePaymentQueryResult result);
 };
 
 struct PaymentItem {
@@ -156,4 +163,5 @@ interface PaymentRequest {
   UpdateWith(PaymentDetails details);
   Abort();
   Complete(PaymentComplete result);
+  CanMakeActivePayment();

[Marijn Kruisselbrink, 2016/11/11 00:00:05]

Would it make sense to make this CanMakeActivePayment() =>
(ActivePaymentQueryResult result), rather than sending the result through a
separate method in PaymentRequestClient? Although I guess the separate method
thing also makes sense since it's the same pattern the existing code uses.

[please use gerrit instead, 2016/11/11 21:11:50]

I'd prefer to stick to the pre-existing pattern in this file.

 };