I am starting to work on it.

I quickly tried by following "allowfullscreen" implementation here
https://codereview.chromium.org/2545693002/

But the frame properties are not getting updated for out-of-process iframes as subframe is not created by that time
https://cs.chromium.org/chromium/src/third_party/WebKit/Source/core/html/HTMLFrameElementBase.cpp?rcl=0&l=120

Please feel free assign to someone else as I'm occupied with few other stuff currently.

rouslan@: Thanks for filing!  And yes, we are on track to turn on the first uses of out-of-process iframes in M56 (for --isolate-extensions mode), so let's aim to get this fixed in M56 if possible.  Let us know if you need any advice on it.

Ah, is this Android only?  We won't be launching --isolate-extensions there (given that there are no extensions on Android).

creis: Was ttps://codereview.chromium.org/2545693002/ moving in the right direction?

Yes, this feature is currently implemented only on Android. Desktop support is coming some time in 2017.

You can reproduce the crash on desktop with some command-line flags:

$ ninja -Cout/lin chrome \
  && out/lin/chrome \
      --enable-experimental-web-platform-features \
      --site-per-process \
      https://rsolomakhin.github.io/pr/iframe/

Good to hear, and thanks.  Still worth fixing, but we won't have any OOPIFs on Android in M56, so might not be as time sensitive.

alexmos@ or dcheng@: Can you take a look at the CL to see if it's on the right track?

#2: Your general approach of following the allowfullscreen implementation should work.  When the subframe gets created, its FrameOwnerProperties are actually propagated in WebLocalFrameImpl::createChildFrame, here: 
https://cs.chromium.org/chromium/src/third_party/WebKit/Source/web/WebLocalFrameImpl.cpp?l=1590
which you did update.  But it seems your WIP CL didn't update allowedToUsePaymentRequest(), which also needs to be able to handle frame->owner() being a RemoteFrameOwner, so perhaps that needs to be worked out also.  Fullscreen has a very similar set of checks in allowedToUseFullscreen().  Happy to help with any further questions/reviewing for this.  

Following up on my #12, duh, I skimmed the CL too quickly and totally misread that you did in fact change allowedToUsePaymentRequest -- sorry.  Looks like you found the real problem already.

The following revision refers to this bug:
  https://chromium.googlesource.com/chromium/src.git/+/a1f17e817c65d8f3e8ba10beee7b43e625f21c04

commit a1f17e817c65d8f3e8ba10beee7b43e625f21c04
Author: sanjoy.pal <sanjoy.pal@samsung.com>
Date: Thu Dec 15 03:39:12 2016

Support allowpaymentrequest with out-of-process iframes

BUG= 669585 

Review-Url: https://codereview.chromium.org/2545693002
Cr-Commit-Position: refs/heads/master@{#438724}

[modify] https://crrev.com/a1f17e817c65d8f3e8ba10beee7b43e625f21c04/chrome/browser/payments/payment_request_impl.cc
[modify] https://crrev.com/a1f17e817c65d8f3e8ba10beee7b43e625f21c04/chrome/browser/payments/payment_request_impl.h
[add] https://crrev.com/a1f17e817c65d8f3e8ba10beee7b43e625f21c04/chrome/browser/payments/site_per_process_payments_browsertest.cc
[modify] https://crrev.com/a1f17e817c65d8f3e8ba10beee7b43e625f21c04/chrome/test/BUILD.gn
[add] https://crrev.com/a1f17e817c65d8f3e8ba10beee7b43e625f21c04/chrome/test/data/payment_request_iframe.html
[add] https://crrev.com/a1f17e817c65d8f3e8ba10beee7b43e625f21c04/chrome/test/data/payment_request_main.html
[modify] https://crrev.com/a1f17e817c65d8f3e8ba10beee7b43e625f21c04/content/common/frame_messages.h
[modify] https://crrev.com/a1f17e817c65d8f3e8ba10beee7b43e625f21c04/content/common/frame_owner_properties.cc
[modify] https://crrev.com/a1f17e817c65d8f3e8ba10beee7b43e625f21c04/content/common/frame_owner_properties.h
[modify] https://crrev.com/a1f17e817c65d8f3e8ba10beee7b43e625f21c04/third_party/WebKit/Source/core/frame/FrameOwner.h
[modify] https://crrev.com/a1f17e817c65d8f3e8ba10beee7b43e625f21c04/third_party/WebKit/Source/core/html/HTMLFrameOwnerElement.h
[modify] https://crrev.com/a1f17e817c65d8f3e8ba10beee7b43e625f21c04/third_party/WebKit/Source/core/html/HTMLIFrameElement.cpp
[modify] https://crrev.com/a1f17e817c65d8f3e8ba10beee7b43e625f21c04/third_party/WebKit/Source/core/html/HTMLIFrameElement.h
[modify] https://crrev.com/a1f17e817c65d8f3e8ba10beee7b43e625f21c04/third_party/WebKit/Source/modules/payments/PaymentRequest.cpp
[modify] https://crrev.com/a1f17e817c65d8f3e8ba10beee7b43e625f21c04/third_party/WebKit/Source/web/FrameLoaderClientImpl.cpp
[modify] https://crrev.com/a1f17e817c65d8f3e8ba10beee7b43e625f21c04/third_party/WebKit/Source/web/RemoteFrameOwner.cpp
[modify] https://crrev.com/a1f17e817c65d8f3e8ba10beee7b43e625f21c04/third_party/WebKit/Source/web/RemoteFrameOwner.h
[modify] https://crrev.com/a1f17e817c65d8f3e8ba10beee7b43e625f21c04/third_party/WebKit/Source/web/WebFrame.cpp
[modify] https://crrev.com/a1f17e817c65d8f3e8ba10beee7b43e625f21c04/third_party/WebKit/Source/web/WebLocalFrameImpl.cpp
[modify] https://crrev.com/a1f17e817c65d8f3e8ba10beee7b43e625f21c04/third_party/WebKit/public/web/WebFrameOwnerProperties.h

Your change meets the bar and is auto-approved for M56 (branch: 2924)

The following revision refers to this bug:
  https://chromium.googlesource.com/chromium/src.git/+/4af576a4562fb7b664732f174f1a112715f31f60

commit 4af576a4562fb7b664732f174f1a112715f31f60
Author: Rouslan Solomakhin <rouslan@chromium.org>
Date: Thu Dec 15 15:28:26 2016

[Merge M-56] Support allowpaymentrequest with out-of-process iframes

BUG= 669585 

Review-Url: https://codereview.chromium.org/2545693002
Cr-Commit-Position: refs/heads/master@{#438724}
(cherry picked from commit a1f17e817c65d8f3e8ba10beee7b43e625f21c04)

Review-Url: https://codereview.chromium.org/2578773003 .
Cr-Commit-Position: refs/branch-heads/2924@{#510}
Cr-Branched-From: 3a87aecc31cd1ffe751dd72c04e5a96a1fc8108a-refs/heads/master@{#433059}

[add] https://crrev.com/4af576a4562fb7b664732f174f1a112715f31f60/chrome/browser/payments/site_per_process_payments_browsertest.cc
[modify] https://crrev.com/4af576a4562fb7b664732f174f1a112715f31f60/chrome/test/BUILD.gn
[add] https://crrev.com/4af576a4562fb7b664732f174f1a112715f31f60/chrome/test/data/payment_request_iframe.html
[add] https://crrev.com/4af576a4562fb7b664732f174f1a112715f31f60/chrome/test/data/payment_request_main.html
[modify] https://crrev.com/4af576a4562fb7b664732f174f1a112715f31f60/content/common/frame_messages.h
[modify] https://crrev.com/4af576a4562fb7b664732f174f1a112715f31f60/content/common/frame_owner_properties.cc
[modify] https://crrev.com/4af576a4562fb7b664732f174f1a112715f31f60/content/common/frame_owner_properties.h
[modify] https://crrev.com/4af576a4562fb7b664732f174f1a112715f31f60/third_party/WebKit/Source/core/frame/FrameOwner.h
[modify] https://crrev.com/4af576a4562fb7b664732f174f1a112715f31f60/third_party/WebKit/Source/core/html/HTMLFrameOwnerElement.h
[modify] https://crrev.com/4af576a4562fb7b664732f174f1a112715f31f60/third_party/WebKit/Source/core/html/HTMLIFrameElement.cpp
[modify] https://crrev.com/4af576a4562fb7b664732f174f1a112715f31f60/third_party/WebKit/Source/core/html/HTMLIFrameElement.h
[modify] https://crrev.com/4af576a4562fb7b664732f174f1a112715f31f60/third_party/WebKit/Source/modules/payments/PaymentRequest.cpp
[modify] https://crrev.com/4af576a4562fb7b664732f174f1a112715f31f60/third_party/WebKit/Source/web/FrameLoaderClientImpl.cpp
[modify] https://crrev.com/4af576a4562fb7b664732f174f1a112715f31f60/third_party/WebKit/Source/web/RemoteFrameOwner.cpp
[modify] https://crrev.com/4af576a4562fb7b664732f174f1a112715f31f60/third_party/WebKit/Source/web/RemoteFrameOwner.h
[modify] https://crrev.com/4af576a4562fb7b664732f174f1a112715f31f60/third_party/WebKit/Source/web/WebFrame.cpp
[modify] https://crrev.com/4af576a4562fb7b664732f174f1a112715f31f60/third_party/WebKit/Source/web/WebLocalFrameImpl.cpp
[modify] https://crrev.com/4af576a4562fb7b664732f174f1a112715f31f60/third_party/WebKit/public/web/WebFrameOwnerProperties.h

The following revision refers to this bug:
  https://chromium.googlesource.com/chromium/src.git/+/319b249e933d384d28339f6676b8781fdc077a38

commit 319b249e933d384d28339f6676b8781fdc077a38
Author: rouslan <rouslan@chromium.org>
Date: Tue Dec 20 00:31:17 2016

Gate web payments iframe support on runtime enabled feature.

OOPIF crash fix in http://crrev.com/2545693002 enabled web payments
iframe support unintentionally. This patch disables it again.

BUG= 669585 

Review-Url: https://codereview.chromium.org/2580893002
Cr-Commit-Position: refs/heads/master@{#439634}

[modify] https://crrev.com/319b249e933d384d28339f6676b8781fdc077a38/third_party/WebKit/Source/modules/payments/PaymentRequest.cpp

Your change meets the bar and is auto-approved for M56 (branch: 2924)

The following revision refers to this bug:
  https://chromium.googlesource.com/chromium/src.git/+/285239b8ac7e7cdae0ce38cd591e8a7b094b720f

commit 285239b8ac7e7cdae0ce38cd591e8a7b094b720f
Author: Rouslan Solomakhin <rouslan@chromium.org>
Date: Tue Dec 20 15:46:03 2016

[Merge M-56] Gate web payments iframe support on runtime enabled feature.

OOPIF crash fix in http://crrev.com/2545693002 enabled web payments
iframe support unintentionally. This patch disables it again.

BUG= 669585 

Review-Url: https://codereview.chromium.org/2580893002
Cr-Commit-Position: refs/heads/master@{#439634}
(cherry picked from commit 319b249e933d384d28339f6676b8781fdc077a38)

Review-Url: https://codereview.chromium.org/2590953002 .
Cr-Commit-Position: refs/branch-heads/2924@{#562}
Cr-Branched-From: 3a87aecc31cd1ffe751dd72c04e5a96a1fc8108a-refs/heads/master@{#433059}

[modify] https://crrev.com/285239b8ac7e7cdae0ce38cd591e8a7b094b720f/third_party/WebKit/Source/modules/payments/PaymentRequest.cpp