iframes with allowpaymentrequest attribute are allowed to make payment requests.

third_party/WebKit/public/web/WebFrameOwnerProperties.h

Index: third_party/WebKit/public/web/WebFrameOwnerProperties.h
diff --git a/third_party/WebKit/public/web/WebFrameOwnerProperties.h b/third_party/WebKit/public/web/WebFrameOwnerProperties.h
index 83df9c14cb206111c18e298f38c795a59191507b..766b846a9ce0adafadceae1df4c7b525f7d78122 100644
--- a/third_party/WebKit/public/web/WebFrameOwnerProperties.h
+++ b/third_party/WebKit/public/web/WebFrameOwnerProperties.h
@@ -18,6 +18,7 @@ struct WebFrameOwnerProperties {
   int marginWidth;
   int marginHeight;
   bool allowFullscreen;
+  bool allowPaymentRequest;
   WebVector<WebPermissionType> delegatedPermissions;
 
   WebFrameOwnerProperties()
@@ -32,11 +33,13 @@ struct WebFrameOwnerProperties {
       int marginWidth,
       int marginHeight,
       bool allowFullscreen,
+      bool allowPaymentRequest,
       const WebVector<WebPermissionType>& delegatedPermissions)
       : scrollingMode(static_cast<ScrollingMode>(scrollingMode)),
         marginWidth(marginWidth),
         marginHeight(marginHeight),
         allowFullscreen(allowFullscreen),
+        allowPaymentRequest(allowPaymentRequest),
         delegatedPermissions(delegatedPermissions) {}
 #endif
 };