[Payments] Implement openWindow for service worker based payment handler

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

Index: third_party/WebKit/Source/modules/payments/PaymentRequestEvent.cpp
diff --git a/third_party/WebKit/Source/modules/payments/PaymentRequestEvent.cpp b/third_party/WebKit/Source/modules/payments/PaymentRequestEvent.cpp
index 748de28bfa536339d42abb6323929f6bd6341052..99ae612217da0c64599bd579d8640bb64de1f5e9 100644
--- a/third_party/WebKit/Source/modules/payments/PaymentRequestEvent.cpp
+++ b/third_party/WebKit/Source/modules/payments/PaymentRequestEvent.cpp
@@ -5,6 +5,8 @@
 #include "modules/payments/PaymentRequestEvent.h"
 
 #include "modules/serviceworkers/RespondWithObserver.h"
+#include "modules/serviceworkers/ServiceWorkerClients.h"
+#include "modules/serviceworkers/ServiceWorkerGlobalScope.h"
 #include "platform/wtf/text/AtomicString.h"
 
 namespace blink {
@@ -53,6 +55,13 @@ const String& PaymentRequestEvent::instrumentKey() const {
   return instrument_key_;
 }
 
+ScriptPromise PaymentRequestEvent::openWindow(ScriptState* script_state,
+                                              const String& url) {
+  return ToServiceWorkerGlobalScope(ExecutionContext::From(script_state))
+      ->clients()
+      ->openWindow(script_state, top_level_origin_, url);
+}
+
 void PaymentRequestEvent::respondWith(ScriptState* script_state,
                                       ScriptPromise script_promise,
                                       ExceptionState& exception_state) {