iframes with allowpaymentrequest attribute are allowed to make payment requests.

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

 /*
  * Copyright (C) 1999 Lars Knoll (knoll@kde.org)
  *           (C) 1999 Antti Koivisto (koivisto@kde.org)
  *           (C) 2000 Simon Hausmann (hausmann@kde.org)
  *           (C) 2001 Dirk Mueller (mueller@kde.org)
  * Copyright (C) 2004, 2006, 2008, 2009 Apple Inc. All rights reserved.
  * Copyright (C) 2009 Ericsson AB. All rights reserved.
  *
  * This library is free software; you can redistribute it and/or
  * modify it under the terms of the GNU Library General Public
@@ skipping 30 matching lines @@
       m_didLoadNonEmptyDocument(false),
       m_sandbox(HTMLIFrameElementSandbox::create(this)),
       m_referrerPolicy(ReferrerPolicyDefault) {}
 
 DEFINE_NODE_FACTORY(HTMLIFrameElement)
 
 DEFINE_TRACE(HTMLIFrameElement) {
   visitor->trace(m_sandbox);
   visitor->trace(m_permissions);
   HTMLFrameElementBase::trace(visitor);
+  Supplementable<HTMLIFrameElement>::trace(visitor);
 }
 
 HTMLIFrameElement::~HTMLIFrameElement() {}
 
 DOMTokenList* HTMLIFrameElement::sandbox() const {
   return m_sandbox.get();
 }
 
 DOMTokenList* HTMLIFrameElement::permissions() const {
   if (!const_cast<HTMLIFrameElement*>(this)->initializePermissionsAttribute())
@@ skipping 145 matching lines @@
 bool HTMLIFrameElement::initializePermissionsAttribute() {
   if (!RuntimeEnabledFeatures::permissionDelegationEnabled())
     return false;
 
   if (!m_permissions)
     m_permissions = HTMLIFrameElementPermissions::create(this);
   return true;
 }
 
 }  // namespace blink