[Payments] Implement payment instrument icons

content/browser/payments/payment_app.proto

Index: content/browser/payments/payment_app.proto
diff --git a/content/browser/payments/payment_app.proto b/content/browser/payments/payment_app.proto
index c2eadb6d7953f5477e3c8a5212bb9c75b2c3ce9b..78a0a23441a0a2494a9489a86d639f53fa2cbd98 100644
--- a/content/browser/payments/payment_app.proto
+++ b/content/browser/payments/payment_app.proto
@@ -13,6 +13,10 @@ message StoredPaymentInstrumentKeyInfoProto {
   optional string key = 2;
 }
 
+message StoredPaymentInstrumentImageObject {
+  optional string src = 1;
+}
+
 message StoredPaymentInstrumentProto {
   optional int64 registration_id = 1;
   optional string instrument_key = 2;
@@ -20,4 +24,6 @@ message StoredPaymentInstrumentProto {
   optional string name = 4;
   repeated string enabled_methods = 5;
   optional string stringified_capabilities = 6;
+  repeated StoredPaymentInstrumentImageObject icons = 7;
+  optional string decoded_instrument_icon = 8;
 }