iframes with allowpaymentrequest attribute are allowed to make payment requests.

third_party/WebKit/Source/core/html/HTMLIFrameElement.h

Index: third_party/WebKit/Source/core/html/HTMLIFrameElement.h
diff --git a/third_party/WebKit/Source/core/html/HTMLIFrameElement.h b/third_party/WebKit/Source/core/html/HTMLIFrameElement.h
index 7d27a3969e2c644ce79adc48a5bfbc9a2ce34ae0..3f82fc9e57286a82e9abe7949c4ab44f78749fa8 100644
--- a/third_party/WebKit/Source/core/html/HTMLIFrameElement.h
+++ b/third_party/WebKit/Source/core/html/HTMLIFrameElement.h
@@ -28,13 +28,17 @@
 #include "core/html/HTMLFrameElementBase.h"
 #include "core/html/HTMLIFrameElementPermissions.h"
 #include "core/html/HTMLIFrameElementSandbox.h"
+#include "platform/Supplementable.h"
 #include "public/platform/WebVector.h"
 #include "public/platform/modules/permissions/WebPermissionType.h"
 
 namespace blink {
 
-class CORE_EXPORT HTMLIFrameElement final : public HTMLFrameElementBase {
+class CORE_EXPORT HTMLIFrameElement final
+    : public HTMLFrameElementBase,
+      public Supplementable<HTMLIFrameElement> {
   DEFINE_WRAPPERTYPEINFO();
+  USING_GARBAGE_COLLECTED_MIXIN(HTMLIFrameElement);
 
  public:
   DECLARE_NODE_FACTORY(HTMLIFrameElement);
@@ -75,6 +79,8 @@ class CORE_EXPORT HTMLIFrameElement final : public HTMLFrameElementBase {
 
   AtomicString csp() const override { return m_csp; }
 
+  bool allowPaymentRequest() const override { return m_allowPaymentRequest; }
+
   const WebVector<WebPermissionType>& delegatedPermissions() const override {
     return m_delegatedPermissions;
   }
@@ -85,6 +91,7 @@ class CORE_EXPORT HTMLIFrameElement final : public HTMLFrameElementBase {
   AtomicString m_csp;
   bool m_didLoadNonEmptyDocument;
   bool m_allowFullscreen;
+  bool m_allowPaymentRequest;
   Member<HTMLIFrameElementSandbox> m_sandbox;
   Member<HTMLIFrameElementPermissions> m_permissions;