The issue is that we do not have a backdrop filter on the blink effect paint property tree nodes. A path to support this is to add the property on effect nodes, then plumb it to cc's effect nodes. There are many open questions to how backdrop filters should really work.

Because backdrop filters are behind a flag and severely broken, we should not block BlinkGenPropertyTrees on this feature. We need to re-think how backdrop filters are implemented.

The following revision refers to this bug:
  https://chromium.googlesource.com/chromium/src.git/+/6e59a6e74dcb299bd7b10c89c03423335ad03bc4

commit 6e59a6e74dcb299bd7b10c89c03423335ad03bc4
Author: Philip Rogers <pdr@chromium.org>
Date: Tue Jul 24 21:02:40 2018

[BlinkGenPropertyTrees] Add a note about backdrop filter failures

Backdrop filters are not supported today. This patch makes this clear in
the BlinkGenPropertyTrees expectations file so folks do not spend time
fixing the tests.

Bug:  854189 
Cq-Include-Trybots: luci.chromium.try:linux_layout_tests_slimming_paint_v2;master.tryserver.blink:linux_trusty_blink_rel
Change-Id: I206c40841c9a1992d122206073afa10dd0953625
Reviewed-on: https://chromium-review.googlesource.com/1148896
Reviewed-by: Chris Harrelson <chrishtr@chromium.org>
Commit-Queue: Philip Rogers <pdr@chromium.org>
Cr-Commit-Position: refs/heads/master@{#577677}
[modify] https://crrev.com/6e59a6e74dcb299bd7b10c89c03423335ad03bc4/third_party/WebKit/LayoutTests/FlagExpectations/enable-blink-gen-property-trees

Should not block.

external/wpt/css/filter-effects/backdrop-filter-isolation.html is also failing with BGPT

These are either fixed (by Mason) or tracked in other bugs.


css3/filters/backdrop-filter-rendering-no-background.html - fixed
css3/filters/backdrop-filter-rendering.html - tracked in https://crbug.com/497522
external/wpt/css/filter-effects/backdrop-filter-isolation.html - tracked in https://crbug.com/497522