iframes with allowpaymentrequest attribute are allowed to make payment requests.

third_party/WebKit/Source/web/FrameLoaderClientImpl.cpp

 /*
  * Copyright (C) 2009, 2012 Google Inc. All rights reserved.
  * Copyright (C) 2011 Apple Inc. All rights reserved.
  *
  * Redistribution and use in source and binary forms, with or without
  * modification, are permitted provided that the following conditions are
  * met:
  *
  *     * Redistributions of source code must retain the above copyright
  * notice, this list of conditions and the following disclaimer.
@@ skipping 876 matching lines @@
 void FrameLoaderClientImpl::didChangeFrameOwnerProperties(
     HTMLFrameElementBase* frameElement) {
   if (!m_webFrame->client())
     return;
 
   m_webFrame->client()->didChangeFrameOwnerProperties(
       WebFrame::fromFrame(frameElement->contentFrame()),
       WebFrameOwnerProperties(
           frameElement->scrollingMode(), frameElement->marginWidth(),
           frameElement->marginHeight(), frameElement->allowFullscreen(),
-          frameElement->csp(), frameElement->delegatedPermissions()));
+          frameElement->allowPaymentRequest(), frameElement->csp(),

[pals, 2016/10/19 12:53:12]

HTMLIFrameElement needs to override allowPaymentRequest()as it is being used
here. 

[haraken, 2016/10/19 15:37:56]

Can we avoid the override by changing the line to something liek:

  HTMLIFrameElementPayments::from(frameElement)->allowPaymentRequest()

?

[pals, 2016/10/20 09:30:07]

Done. 

+          frameElement->delegatedPermissions()));
 }
 
 void FrameLoaderClientImpl::dispatchWillStartUsingPeerConnectionHandler(
     WebRTCPeerConnectionHandler* handler) {
   m_webFrame->client()->willStartUsingPeerConnectionHandler(handler);
 }
 
 bool FrameLoaderClientImpl::allowWebGL(bool enabledPerSettings) {
   if (m_webFrame->client())
     return m_webFrame->client()->allowWebGL(enabledPerSettings);
@@ skipping 83 matching lines @@
 WebDevToolsAgentImpl* FrameLoaderClientImpl::devToolsAgent() {
   return WebLocalFrameImpl::fromFrame(m_webFrame->frame()->localFrameRoot())
       ->devToolsAgentImpl();
 }
 
 KURL FrameLoaderClientImpl::overrideFlashEmbedWithHTML(const KURL& url) {
   return m_webFrame->client()->overrideFlashEmbedWithHTML(WebURL(url));
 }
 
 }  // namespace blink