iframes with allowpaymentrequest attribute are allowed to make payment requests.

third_party/WebKit/Source/web/RemoteFrameOwner.h

Index: third_party/WebKit/Source/web/RemoteFrameOwner.h
diff --git a/third_party/WebKit/Source/web/RemoteFrameOwner.h b/third_party/WebKit/Source/web/RemoteFrameOwner.h
index 5f54fea087fcdf6e7c963c180be34821dfd8b1f3..91348bc09cc6777651b1e593604eae86b89a6471 100644
--- a/third_party/WebKit/Source/web/RemoteFrameOwner.h
+++ b/third_party/WebKit/Source/web/RemoteFrameOwner.h
@@ -40,6 +40,7 @@ class RemoteFrameOwner final
   int marginWidth() const override { return m_marginWidth; }
   int marginHeight() const override { return m_marginHeight; }
   bool allowFullscreen() const override { return m_allowFullscreen; }
+  bool allowPaymentRequest() const override { return m_allowPaymentRequest; }
   const WebVector<WebPermissionType>& delegatedPermissions() const override {
     return m_delegatedPermissions;
   }
@@ -50,6 +51,9 @@ class RemoteFrameOwner final
   void setAllowFullscreen(bool allowFullscreen) {
     m_allowFullscreen = allowFullscreen;
   }
+  void setAllowPaymentRequest(bool allowPaymentRequest) {
+    m_allowPaymentRequest = allowPaymentRequest;
+  }
   void setDelegatedpermissions(
       const WebVector<WebPermissionType>& delegatedPermissions) {
     m_delegatedPermissions = delegatedPermissions;
@@ -71,6 +75,7 @@ class RemoteFrameOwner final
   int m_marginWidth;
   int m_marginHeight;
   bool m_allowFullscreen;
+  bool m_allowPaymentRequest;
   WebVector<WebPermissionType> m_delegatedPermissions;
 };