The following revision refers to this bug:
  https://chromium.googlesource.com/chromium/src.git/+/d3a2246b2215813868dddb8e81ced3103e137f20

commit d3a2246b2215813868dddb8e81ced3103e137f20
Author: Philip Rogers <pdr@chromium.org>
Date: Thu Oct 12 19:48:39 2017

[root layer scrolls] Fix composited-scroll.js tests

composited-scroll.js checked for any scrolling contents layer
and with Root Layer Scrolling (RLS) there will always be at
least one scrolling contents layer. This patch updates
composited-scroll.js to check specific scrolling element layers
instead of the entire page's layers.

Bug:  773885 
Change-Id: I48c81c28a6dc04d2d8b749bd866125f99adf28aa
Reviewed-on: https://chromium-review.googlesource.com/714297
Commit-Queue: Philip Rogers <pdr@chromium.org>
Reviewed-by: Steve Kobes <skobes@chromium.org>
Cr-Commit-Position: refs/heads/master@{#508390}
[modify] https://crrev.com/d3a2246b2215813868dddb8e81ced3103e137f20/third_party/WebKit/LayoutTests/FlagExpectations/root-layer-scrolls
[modify] https://crrev.com/d3a2246b2215813868dddb8e81ced3103e137f20/third_party/WebKit/LayoutTests/compositing/overflow/ancestor-with-clip-path.html
[modify] https://crrev.com/d3a2246b2215813868dddb8e81ced3103e137f20/third_party/WebKit/LayoutTests/compositing/overflow/descendant-with-clip-path.html
[modify] https://crrev.com/d3a2246b2215813868dddb8e81ced3103e137f20/third_party/WebKit/LayoutTests/compositing/overflow/opt-in-if-composited.html
[modify] https://crrev.com/d3a2246b2215813868dddb8e81ced3103e137f20/third_party/WebKit/LayoutTests/compositing/overflow/overflow-scroll-background-opaque-to-transparent.html
[modify] https://crrev.com/d3a2246b2215813868dddb8e81ced3103e137f20/third_party/WebKit/LayoutTests/compositing/overflow/overflow-scroll-background-transparent-to-opaque.html
[modify] https://crrev.com/d3a2246b2215813868dddb8e81ced3103e137f20/third_party/WebKit/LayoutTests/compositing/overflow/overflow-scroll-with-opaque-background-will-change.html
[modify] https://crrev.com/d3a2246b2215813868dddb8e81ced3103e137f20/third_party/WebKit/LayoutTests/compositing/overflow/overflow-scroll-with-opaque-background.html
[modify] https://crrev.com/d3a2246b2215813868dddb8e81ced3103e137f20/third_party/WebKit/LayoutTests/compositing/overflow/overflow-scroll-with-pointer-events-toggle-expected.txt
[modify] https://crrev.com/d3a2246b2215813868dddb8e81ced3103e137f20/third_party/WebKit/LayoutTests/compositing/overflow/overflow-scroll-with-pointer-events-toggle.html
[modify] https://crrev.com/d3a2246b2215813868dddb8e81ced3103e137f20/third_party/WebKit/LayoutTests/compositing/overflow/overflow-scroll-with-transparent-background.html
[modify] https://crrev.com/d3a2246b2215813868dddb8e81ced3103e137f20/third_party/WebKit/LayoutTests/compositing/overflow/resources/composited-scroll.js
[modify] https://crrev.com/d3a2246b2215813868dddb8e81ced3103e137f20/third_party/WebKit/LayoutTests/compositing/overflow/scroller-with-border-radius.html