This would be fantastic for FB as it's the main thing blocking us from making the wheel event passive. 

Since this is an OWP launch bug, putting "ship" in the title instead of "implement".  

CSSWG has resolved to work on this via WICG: https://github.com/w3c/csswg-drafts/issues/769#issuecomment-293111694.  Next step is probably for someone to copy Majid's justification from discourse into an explainer.md and create a new GitHub repo that we move to the WICG org.

The repo is now live:
https://github.com/WICG/scroll-boundary-behavior/issues

Please contribution to the discussion. I'll start a spec draft in the repo after a bit more discussion (or lack of) has happened.

I think the amount of the discussion that has happened in the CSSOM issue and WICG thread is enough for us to start the draft spec. I don't think without the detailed spec we will get any more feedback at this point.

Thanks, I'll start a draft. I did file a few issues where input would help in writing the draft but I can start now:
https://github.com/WICG/scroll-boundary-behavior/issues

Draft is posted:
https://wicg.github.io/scroll-boundary-behavior/

The following revision refers to this bug:
  https://chromium.googlesource.com/chromium/src.git/+/55ed8ccd43eadef318b5e7a6bcf2519b078b1213

commit 55ed8ccd43eadef318b5e7a6bcf2519b078b1213
Author: sunyunjia <sunyunjia@chromium.org>
Date: Wed Jul 19 01:19:11 2017

Implement CSS: scroll-boundary-behavior.

CSS: scroll-boundary-behavior allows developers to specify whether the scroll
should be propagated to its ancestors. This is different from scroll
latching, in the way that when latching is turned on, a gesture will be
limited to a single element, but scroll-boundary-behavior will affect
propagation when the latch is being targeted at the beginning of the gesture.

This patch implements scroll-boundary-behavior: none, by cutting off the
scroll chain when the scrollNode has the property, so the scroll will not be
propagated. After this patch lands, we will implement scroll-boundary-behavior:
contain, which controls overscroll UI affordance such as glow/bounce etc.

BUG= 672921 
CQ_INCLUDE_TRYBOTS=master.tryserver.blink:linux_trusty_blink_rel;master.tryserver.chromium.linux:linux_layout_tests_slimming_paint_v2

Review-Url: https://codereview.chromium.org/2769793002
Cr-Commit-Position: refs/heads/master@{#487702}

[modify] https://crrev.com/55ed8ccd43eadef318b5e7a6bcf2519b078b1213/cc/blink/web_layer_impl.cc
[modify] https://crrev.com/55ed8ccd43eadef318b5e7a6bcf2519b078b1213/cc/blink/web_layer_impl.h
[add] https://crrev.com/55ed8ccd43eadef318b5e7a6bcf2519b078b1213/cc/input/scroll_boundary_behavior.h
[modify] https://crrev.com/55ed8ccd43eadef318b5e7a6bcf2519b078b1213/cc/layers/layer.cc
[modify] https://crrev.com/55ed8ccd43eadef318b5e7a6bcf2519b078b1213/cc/layers/layer.h
[modify] https://crrev.com/55ed8ccd43eadef318b5e7a6bcf2519b078b1213/cc/layers/layer_impl_test_properties.cc
[modify] https://crrev.com/55ed8ccd43eadef318b5e7a6bcf2519b078b1213/cc/layers/layer_impl_test_properties.h
[modify] https://crrev.com/55ed8ccd43eadef318b5e7a6bcf2519b078b1213/cc/trees/layer_tree_host_impl.cc
[modify] https://crrev.com/55ed8ccd43eadef318b5e7a6bcf2519b078b1213/cc/trees/layer_tree_host_impl_unittest.cc
[modify] https://crrev.com/55ed8ccd43eadef318b5e7a6bcf2519b078b1213/cc/trees/property_tree_builder.cc
[modify] https://crrev.com/55ed8ccd43eadef318b5e7a6bcf2519b078b1213/cc/trees/scroll_node.cc
[modify] https://crrev.com/55ed8ccd43eadef318b5e7a6bcf2519b078b1213/cc/trees/scroll_node.h
[add] https://crrev.com/55ed8ccd43eadef318b5e7a6bcf2519b078b1213/third_party/WebKit/LayoutTests/fast/scroll-behavior/scroll-boundary-behavior.html
[modify] https://crrev.com/55ed8ccd43eadef318b5e7a6bcf2519b078b1213/third_party/WebKit/LayoutTests/webexposed/css-properties-as-js-properties-expected.txt
[modify] https://crrev.com/55ed8ccd43eadef318b5e7a6bcf2519b078b1213/third_party/WebKit/LayoutTests/webexposed/css-property-listing-expected.txt
[modify] https://crrev.com/55ed8ccd43eadef318b5e7a6bcf2519b078b1213/third_party/WebKit/Source/core/css/CSSProperties.json5
[modify] https://crrev.com/55ed8ccd43eadef318b5e7a6bcf2519b078b1213/third_party/WebKit/Source/core/css/CSSValueKeywords.json5
[modify] https://crrev.com/55ed8ccd43eadef318b5e7a6bcf2519b078b1213/third_party/WebKit/Source/core/css/ComputedStyleCSSValueMapping.cpp
[modify] https://crrev.com/55ed8ccd43eadef318b5e7a6bcf2519b078b1213/third_party/WebKit/Source/core/css/StylePropertySerializer.cpp
[modify] https://crrev.com/55ed8ccd43eadef318b5e7a6bcf2519b078b1213/third_party/WebKit/Source/core/css/parser/CSSParserFastPaths.cpp
[modify] https://crrev.com/55ed8ccd43eadef318b5e7a6bcf2519b078b1213/third_party/WebKit/Source/core/css/parser/CSSPropertyParser.cpp
[modify] https://crrev.com/55ed8ccd43eadef318b5e7a6bcf2519b078b1213/third_party/WebKit/Source/core/frame/UseCounter.cpp
[modify] https://crrev.com/55ed8ccd43eadef318b5e7a6bcf2519b078b1213/third_party/WebKit/Source/core/input/ScrollManager.cpp
[modify] https://crrev.com/55ed8ccd43eadef318b5e7a6bcf2519b078b1213/third_party/WebKit/Source/core/layout/compositing/CompositedLayerMapping.cpp
[modify] https://crrev.com/55ed8ccd43eadef318b5e7a6bcf2519b078b1213/third_party/WebKit/Source/core/layout/compositing/CompositedLayerMapping.h
[modify] https://crrev.com/55ed8ccd43eadef318b5e7a6bcf2519b078b1213/third_party/WebKit/Source/platform/RuntimeEnabledFeatures.json5
[modify] https://crrev.com/55ed8ccd43eadef318b5e7a6bcf2519b078b1213/third_party/WebKit/Source/platform/graphics/GraphicsLayer.cpp
[modify] https://crrev.com/55ed8ccd43eadef318b5e7a6bcf2519b078b1213/third_party/WebKit/Source/platform/graphics/GraphicsLayer.h
[modify] https://crrev.com/55ed8ccd43eadef318b5e7a6bcf2519b078b1213/third_party/WebKit/Source/web/AssertMatchingEnums.cpp
[modify] https://crrev.com/55ed8ccd43eadef318b5e7a6bcf2519b078b1213/third_party/WebKit/public/platform/WebLayer.h
[add] https://crrev.com/55ed8ccd43eadef318b5e7a6bcf2519b078b1213/third_party/WebKit/public/platform/WebScrollBoundaryBehavior.h
[modify] https://crrev.com/55ed8ccd43eadef318b5e7a6bcf2519b078b1213/tools/metrics/histograms/enums.xml

Our users hate setting this flag daily, admin console needs to be able to push this. 

The following revision refers to this bug:
  https://chromium.googlesource.com/chromium/src.git/+/56279196a0b5a130d32c3cdb3ef4fc0deac79f2b

commit 56279196a0b5a130d32c3cdb3ef4fc0deac79f2b
Author: Eric Willigers <ericwilligers@chromium.org>
Date: Tue Sep 12 22:58:39 2017

CSS: Serialize both scroll-boundary-behavior words

scroll-boundary-behavior is a shorthand containing
scroll-boundary-behavior-x and scroll-boundary-behavior-y.

If only one value is specified, the second value defaults
to the same value.

Spec:
https://wicg.github.io/scroll-boundary-behavior/#scroll-boundary-behavior-properties

BUG= 672921 

Change-Id: Ib924802ac441f0ddbe9d1f360c7d9d91ff5b80c6
Reviewed-on: https://chromium-review.googlesource.com/662480
Reviewed-by: Majid Valipour <majidvp@chromium.org>
Commit-Queue: Eric Willigers <ericwilligers@chromium.org>
Cr-Commit-Position: refs/heads/master@{#501437}
[add] https://crrev.com/56279196a0b5a130d32c3cdb3ef4fc0deac79f2b/third_party/WebKit/LayoutTests/fast/css/getComputedStyle/getComputedStyle-scrollBoundaryBehavior-serialization.html
[modify] https://crrev.com/56279196a0b5a130d32c3cdb3ef4fc0deac79f2b/third_party/WebKit/Source/core/css/ComputedStyleCSSValueMapping.cpp
[modify] https://crrev.com/56279196a0b5a130d32c3cdb3ef4fc0deac79f2b/third_party/WebKit/Source/core/css/StylePropertySerializer.cpp

This issue has been automatically relabelled type=task because type=launch-owp issues are now officially deprecated. The deprecation is because they were creating confusion about how to get launch approvals, which should be instead done via type=launch issues.

We recommend this issue be used for implementation tracking (for public visibility), but if you already have an issue for that, you may mark this as duplicate.

For more details see here: https://docs.google.com/document/d/1JA6RohjtZQc26bTrGoIE_bSXGXUDQz8vc6G0n_sZJ2o/edit

For any questions, please contact owencm, sshruthi, larforge

re #18 - Runtime enabled experimental feature flags are not really meant to be used in production. In this case the feature is being planned to be in M63. I am not sure what is your usecase but while you are waiting for that release to hit stable, it may be possible to use alternative workarounds for it.

The following revision refers to this bug:
  https://chromium.googlesource.com/chromium/src.git/+/20e1cdce61d72f5540aa8175bc838f3e20aa2e4f

commit 20e1cdce61d72f5540aa8175bc838f3e20aa2e4f
Author: Majid Valipour <majidvp@chromium.org>
Date: Tue Sep 19 19:06:49 2017

Turn ScrollBoundaryBehavior runtime feature on by default

Blink intent-to-ship: https://groups.google.com/a/chromium.org/d/msg/blink-dev/OqBNF2efmFA/3ByBUKyaCgAJ
Draft Specification: https://wicg.github.io/scroll-boundary-behavior/

Bug:  672921 
Change-Id: I18b1475def2346faeb60aa46085328f4d60f8470
Reviewed-on: https://chromium-review.googlesource.com/663624
Commit-Queue: Majid Valipour <majidvp@chromium.org>
Reviewed-by: Chris Harrelson <chrishtr@chromium.org>
Cr-Commit-Position: refs/heads/master@{#502907}
[modify] https://crrev.com/20e1cdce61d72f5540aa8175bc838f3e20aa2e4f/third_party/WebKit/LayoutTests/virtual/stable/webexposed/css-properties-as-js-properties-expected.txt
[modify] https://crrev.com/20e1cdce61d72f5540aa8175bc838f3e20aa2e4f/third_party/WebKit/LayoutTests/virtual/stable/webexposed/css-property-listing-expected.txt
[modify] https://crrev.com/20e1cdce61d72f5540aa8175bc838f3e20aa2e4f/third_party/WebKit/Source/platform/runtime_enabled_features.json5

M63 stable launch is coming soon and this feature is targeted for M63 Stable, please have cross functional bits flipped ASAP. Thank you.

So is this overscroll-behavior or scroll-boundary-behavior? Is it going to be shipped in M63? 

Yes, this is renamed from scroll-boundary-behavior and is going to be shipped in M63.