Mark IFrame support in PaymentRequest experimental

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

Index: third_party/WebKit/Source/modules/payments/PaymentRequest.cpp
diff --git a/third_party/WebKit/Source/modules/payments/PaymentRequest.cpp b/third_party/WebKit/Source/modules/payments/PaymentRequest.cpp
index f67b63bede62e3795377d09323f5ff31669c1382..657b8590fc0bc3c6e90c35ce32a05f734164eeaf 100644
--- a/third_party/WebKit/Source/modules/payments/PaymentRequest.cpp
+++ b/third_party/WebKit/Source/modules/payments/PaymentRequest.cpp
@@ -29,6 +29,7 @@
 #include "modules/payments/PaymentsValidators.h"
 #include "mojo/public/cpp/bindings/interface_request.h"
 #include "mojo/public/cpp/bindings/wtf_array.h"
+#include "platform/RuntimeEnabledFeatures.h"
 #include "platform/mojo/MojoHelper.h"
 #include "public/platform/InterfaceProvider.h"
 #include "public/platform/Platform.h"
@@ -732,8 +733,10 @@ PaymentRequest::PaymentRequest(ScriptState* scriptState,
 
   if (!allowedToUsePaymentRequest(scriptState->domWindow()->frame())) {
     exceptionState.throwSecurityError(
-        "Must be in a top-level browsing context or an iframe needs to specify "
-        "'allowpaymentrequest' explicitly");
+        RuntimeEnabledFeatures::paymentRequestIFrameEnabled()
+            ? "Must be in a top-level browsing context or an iframe needs to "
+              "specify 'allowpaymentrequest' explicitly"
+            : "Must be in a top-level browsing context");
     return;
   }