Add test to check that the payment response details field is a JSON-serializable object.

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

Index: third_party/WebKit/Source/modules/payments/PaymentResponseTest.cpp
diff --git a/third_party/WebKit/Source/modules/payments/PaymentResponseTest.cpp b/third_party/WebKit/Source/modules/payments/PaymentResponseTest.cpp
index 35da551475c3540bd99e0d0fd453386bf6539029..a683458a27bf5385b82e161d780763bacddc7eaf 100644
--- a/third_party/WebKit/Source/modules/payments/PaymentResponseTest.cpp
+++ b/third_party/WebKit/Source/modules/payments/PaymentResponseTest.cpp
@@ -69,6 +69,19 @@ TEST(PaymentResponseTest, DataCopiedOver)
     EXPECT_EQ(123, transactionId.v8Value().As<v8::Number>()->Value());
 }
 
+TEST(PaymentResponseTest, PaymentResponseDetailsJSONObject)
+{
+    V8TestingScope scope;
+    mojom::blink::PaymentResponsePtr input = buildPaymentResponseForTest();
+    input->stringified_details = "transactionId";
+    MockPaymentCompleter* completeCallback = new MockPaymentCompleter;
+    PaymentResponse output(std::move(input), completeCallback);
+
+    ScriptValue details = output.details(scope.getScriptState(), scope.getExceptionState());
+
+    ASSERT_TRUE(scope.getExceptionState().hadException());
+}
+
 TEST(PaymentResponseTest, CompleteCalledWithSuccess)
 {
     V8TestingScope scope;