Nicolas, any chance you could take this one?

Could you create a paint-timing folder in https://github.com/w3c/web-platform-tests/ and add an OWNERS file with yourself? I don't have write access to that repository and adding OWNERS in chromium doesn't upstream.

The following revision refers to this bug:
  https://chromium.googlesource.com/chromium/src.git/+/f3bcf226541a0b7ebb25284e5d364e346d9924ce

commit f3bcf226541a0b7ebb25284e5d364e346d9924ce
Author: Nicolas Pena <npm@chromium.org>
Date: Fri Sep 08 18:08:30 2017

Move paint-timing tests to external/wpt

This CL moves paint-timing tests to external/wpt. It avoids the use of
testRunner, but to do so adds a virtual test to enable threaded
compositing so that the swap promises are resolved. The non-virtual
version is marked as Skip since it will timeout.

Bug:  chromium:720047 
Cq-Include-Trybots: master.tryserver.chromium.linux:linux_layout_tests_slimming_paint_v2
Change-Id: Idf795b10d59c7d6629bad3d7a1271a711652eeaf
Reviewed-on: https://chromium-review.googlesource.com/638471
Reviewed-by: Timothy Dresser <tdresser@chromium.org>
Commit-Queue: Nicolás Peña <npm@chromium.org>
Cr-Commit-Position: refs/heads/master@{#500620}
[modify] https://crrev.com/f3bcf226541a0b7ebb25284e5d364e346d9924ce/third_party/WebKit/LayoutTests/FlagExpectations/root-layer-scrolls
[modify] https://crrev.com/f3bcf226541a0b7ebb25284e5d364e346d9924ce/third_party/WebKit/LayoutTests/TestExpectations
[modify] https://crrev.com/f3bcf226541a0b7ebb25284e5d364e346d9924ce/third_party/WebKit/LayoutTests/VirtualTestSuites
[add] https://crrev.com/f3bcf226541a0b7ebb25284e5d364e346d9924ce/third_party/WebKit/LayoutTests/external/wpt/paint-timing/OWNERS
[add] https://crrev.com/f3bcf226541a0b7ebb25284e5d364e346d9924ce/third_party/WebKit/LayoutTests/external/wpt/paint-timing/basetest.html
[add] https://crrev.com/f3bcf226541a0b7ebb25284e5d364e346d9924ce/third_party/WebKit/LayoutTests/external/wpt/paint-timing/first-contentful-bg-image.html
[add] https://crrev.com/f3bcf226541a0b7ebb25284e5d364e346d9924ce/third_party/WebKit/LayoutTests/external/wpt/paint-timing/first-contentful-canvas.html
[add] https://crrev.com/f3bcf226541a0b7ebb25284e5d364e346d9924ce/third_party/WebKit/LayoutTests/external/wpt/paint-timing/first-contentful-image.html
[add] https://crrev.com/f3bcf226541a0b7ebb25284e5d364e346d9924ce/third_party/WebKit/LayoutTests/external/wpt/paint-timing/first-contentful-paint.html
[add] https://crrev.com/f3bcf226541a0b7ebb25284e5d364e346d9924ce/third_party/WebKit/LayoutTests/external/wpt/paint-timing/first-contentful-svg.html
[add] https://crrev.com/f3bcf226541a0b7ebb25284e5d364e346d9924ce/third_party/WebKit/LayoutTests/external/wpt/paint-timing/first-paint-bg-color.html
[add] https://crrev.com/f3bcf226541a0b7ebb25284e5d364e346d9924ce/third_party/WebKit/LayoutTests/external/wpt/paint-timing/first-paint-only.html
[rename] https://crrev.com/f3bcf226541a0b7ebb25284e5d364e346d9924ce/third_party/WebKit/LayoutTests/external/wpt/paint-timing/resources/circle.svg
[rename] https://crrev.com/f3bcf226541a0b7ebb25284e5d364e346d9924ce/third_party/WebKit/LayoutTests/external/wpt/paint-timing/resources/circles.png
[delete] https://crrev.com/06cf072205859c34cabe735ea52d51e7b2872cb4/third_party/WebKit/LayoutTests/http/tests/performance-timing/paint-timing/basetest.html
[delete] https://crrev.com/06cf072205859c34cabe735ea52d51e7b2872cb4/third_party/WebKit/LayoutTests/http/tests/performance-timing/paint-timing/first-contentful-bg-image.html
[delete] https://crrev.com/06cf072205859c34cabe735ea52d51e7b2872cb4/third_party/WebKit/LayoutTests/http/tests/performance-timing/paint-timing/first-contentful-canvas.html
[delete] https://crrev.com/06cf072205859c34cabe735ea52d51e7b2872cb4/third_party/WebKit/LayoutTests/http/tests/performance-timing/paint-timing/first-contentful-image.html
[delete] https://crrev.com/06cf072205859c34cabe735ea52d51e7b2872cb4/third_party/WebKit/LayoutTests/http/tests/performance-timing/paint-timing/first-contentful-paint.html
[delete] https://crrev.com/06cf072205859c34cabe735ea52d51e7b2872cb4/third_party/WebKit/LayoutTests/http/tests/performance-timing/paint-timing/first-contentful-svg.html
[delete] https://crrev.com/06cf072205859c34cabe735ea52d51e7b2872cb4/third_party/WebKit/LayoutTests/http/tests/performance-timing/paint-timing/first-paint-bg-color.html
[delete] https://crrev.com/06cf072205859c34cabe735ea52d51e7b2872cb4/third_party/WebKit/LayoutTests/http/tests/performance-timing/paint-timing/first-paint-only.html
[add] https://crrev.com/f3bcf226541a0b7ebb25284e5d364e346d9924ce/third_party/WebKit/LayoutTests/virtual/paint-timing/external/wpt/paint-timing/README.txt

Nothing left to do here.