[Payments] Implement openWindow for service worker based payment handler

third_party/WebKit/Source/modules/payments/PaymentRequestEvent.idl

Index: third_party/WebKit/Source/modules/payments/PaymentRequestEvent.idl
diff --git a/third_party/WebKit/Source/modules/payments/PaymentRequestEvent.idl b/third_party/WebKit/Source/modules/payments/PaymentRequestEvent.idl
index 15e18ecca676dd712840250d0300de970396c624..0b9cffe9e4c158fabb82ce8679e54a0cf161cace 100644
--- a/third_party/WebKit/Source/modules/payments/PaymentRequestEvent.idl
+++ b/third_party/WebKit/Source/modules/payments/PaymentRequestEvent.idl
@@ -18,8 +18,6 @@
     readonly attribute sequence<PaymentDetailsModifier> modifiers;
     readonly attribute DOMString instrumentKey;
 
-    // TODO(gogerald): We should implement this function.
-    // Please see: http://crbug.com/720027
-    // Promise<WindowClient> openWindow(USVString url);
+    [CallWith=ScriptState] Promise<WindowClient?> openWindow(USVString url);

[please use gerrit instead, 2017/05/25 14:53:27]

The spec does not have a question mark next to WindowClient, meaning that null
cannot be returned, I believe. Can you explain the need for the question mark
here? If it's an implementation requirement, then please file a bug on
https://github.io/w3c/payment-handler/issues.

[gogerald1, 2017/05/25 16:53:32]

It must have question mark as for service worker, the openWindow algorithm in
the spec also mentioned windowClient could be null.
reported this issue, https://github.com/w3c/payment-handler/issues/163

[zino, 2017/05/25 17:02:42]

I think it is correct that this function does not return null.
Unlike clients.openWindow(), this function will create controlled window client
only.
According to the spec[1] 8-4 section, if the origin is not the same as the
service worker client origin associated with the payment handler, then,
reject promise with SecurityError.

[1] https://w3c.github.io/payment-handler/#dfn-open-window-algorithm

[gogerald1, 2017/05/29 22:13:16]

Done.

     [CallWith=ScriptState, RaisesException] void respondWith(Promise<PaymentResponse> response);
 };