The following revision refers to this bug:
  https://chromium.googlesource.com/chromium/src.git/+/7263ff4c7fd91d83af303428614392fa610b2f8c

commit 7263ff4c7fd91d83af303428614392fa610b2f8c
Author: Findit <findit-for-me@appspot.gserviceaccount.com>
Date: Fri Nov 16 23:17:18 2018

Revert "[BlinkGenPropertyTrees] Associate each cc::KeyframeModel with ElementId"

This reverts commit 4391edc08203d66f87950a080cbfbfcb2f2b9d22.

Reason for revert:

Findit (https://goo.gl/kROfz5) identified CL at revision 608932 as the
culprit for flakes in the build cycles as shown on:
https://findit-for-me.appspot.com/waterfall/flake/flake-culprit?key=ag9zfmZpbmRpdC1mb3ItbWVyQwsSDEZsYWtlQ3VscHJpdCIxY2hyb21pdW0vNDM5MWVkYzA4MjAzZDY2Zjg3OTUwYTA4MGNiZmJmY2IyZjJiOWQyMgw

Sample Failed Build: https://ci.chromium.org/buildbot/chromium.webkit/WebKit%20Linux%20Trusty%20Leak/26490

Sample Failed Step: webkit_layout_tests

Sample Flaky Test: virtual/threaded/animations/composited-filter-animation.html

Original change's description:
> [BlinkGenPropertyTrees] Associate each cc::KeyframeModel with ElementId
> 
> In BGPT, each KeyframeModel on a given Animation may need to animate a different
> ElementId, as the various effects of an element are split into multiple
> different nodes in some of the same node trees. This change sets the ElementId
> on the keyframe model and uses that when applying mutations.
> 
> Since animations currently expect to look for the existence of a single element,
> this patch also modifies PaintPropertyBuilder to construct each node type that
> may be needed for an animation when any property is being animated on an element
> and then uses the kPrimaryEffect id to check whether this has happened.
> 
> This also makes several changes to plumb the proper list of element ids:
> - Register all ancestor ElementIds in PaintArtifactCompositor::Update.
> - Synchronize registered ids during commit.
> - Synchronize registered ids during activation.
> 
> Cq-Include-Trybots: luci.chromium.try:linux-blink-gen-property-trees;luci.chromium.try:linux_layout_tests_slimming_paint_v2;master.tryserver.blink:linux_trusty_blink_rel
> Bug:  896549 
> Change-Id: I717822a1ca174658ef792005e76613a5033f4f6a
> Reviewed-on: https://chromium-review.googlesource.com/c/1297305
> Reviewed-by: Philip Rogers <pdr@chromium.org>
> Commit-Queue: Robert Flack <flackr@chromium.org>
> Cr-Commit-Position: refs/heads/master@{#608932}

Change-Id: Idaed0e8efd9ea459af64a2201bb53ba2d58d2a28
No-Presubmit: true
No-Tree-Checks: true
No-Try: true
Bug:  896549 ,  906268 
Cq-Include-Trybots: luci.chromium.try:linux-blink-gen-property-trees;luci.chromium.try:linux_layout_tests_slimming_paint_v2;master.tryserver.blink:linux_trusty_blink_rel
Reviewed-on: https://chromium-review.googlesource.com/c/1341060
Cr-Commit-Position: refs/heads/master@{#609018}
[modify] https://crrev.com/7263ff4c7fd91d83af303428614392fa610b2f8c/cc/animation/element_animations.cc
[modify] https://crrev.com/7263ff4c7fd91d83af303428614392fa610b2f8c/cc/animation/element_animations.h
[modify] https://crrev.com/7263ff4c7fd91d83af303428614392fa610b2f8c/cc/animation/keyframe_model.cc
[modify] https://crrev.com/7263ff4c7fd91d83af303428614392fa610b2f8c/cc/animation/keyframe_model.h
[modify] https://crrev.com/7263ff4c7fd91d83af303428614392fa610b2f8c/cc/trees/layer_tree_host.cc
[modify] https://crrev.com/7263ff4c7fd91d83af303428614392fa610b2f8c/cc/trees/layer_tree_host.h
[modify] https://crrev.com/7263ff4c7fd91d83af303428614392fa610b2f8c/cc/trees/layer_tree_impl.cc
[modify] https://crrev.com/7263ff4c7fd91d83af303428614392fa610b2f8c/cc/trees/layer_tree_impl.h
[modify] https://crrev.com/7263ff4c7fd91d83af303428614392fa610b2f8c/cc/trees/tree_synchronizer.cc
[modify] https://crrev.com/7263ff4c7fd91d83af303428614392fa610b2f8c/third_party/WebKit/LayoutTests/FlagExpectations/enable-blink-gen-property-trees
[modify] https://crrev.com/7263ff4c7fd91d83af303428614392fa610b2f8c/third_party/WebKit/LayoutTests/FlagExpectations/enable-slimming-paint-v2
[delete] https://crrev.com/ee59bc4250b3d20da2f3e5c555ffd0324b5816c9/third_party/WebKit/LayoutTests/animations/composited-filter-animation-expected.html
[delete] https://crrev.com/ee59bc4250b3d20da2f3e5c555ffd0324b5816c9/third_party/WebKit/LayoutTests/animations/composited-filter-animation.html
[modify] https://crrev.com/7263ff4c7fd91d83af303428614392fa610b2f8c/third_party/blink/renderer/core/animation/animation_test.cc
[modify] https://crrev.com/7263ff4c7fd91d83af303428614392fa610b2f8c/third_party/blink/renderer/core/animation/compositor_animations.cc
[modify] https://crrev.com/7263ff4c7fd91d83af303428614392fa610b2f8c/third_party/blink/renderer/core/animation/compositor_animations.h
[modify] https://crrev.com/7263ff4c7fd91d83af303428614392fa610b2f8c/third_party/blink/renderer/core/animation/compositor_animations_test.cc
[modify] https://crrev.com/7263ff4c7fd91d83af303428614392fa610b2f8c/third_party/blink/renderer/core/exported/web_layer_test.cc
[modify] https://crrev.com/7263ff4c7fd91d83af303428614392fa610b2f8c/third_party/blink/renderer/core/paint/paint_property_tree_builder.cc
[modify] https://crrev.com/7263ff4c7fd91d83af303428614392fa610b2f8c/third_party/blink/renderer/core/paint/paint_property_tree_builder_test.cc
[modify] https://crrev.com/7263ff4c7fd91d83af303428614392fa610b2f8c/third_party/blink/renderer/core/paint/paint_property_tree_update_tests.cc
[modify] https://crrev.com/7263ff4c7fd91d83af303428614392fa610b2f8c/third_party/blink/renderer/platform/BUILD.gn
[modify] https://crrev.com/7263ff4c7fd91d83af303428614392fa610b2f8c/third_party/blink/renderer/platform/animation/compositor_keyframe_model.cc
[modify] https://crrev.com/7263ff4c7fd91d83af303428614392fa610b2f8c/third_party/blink/renderer/platform/animation/compositor_keyframe_model.h
[modify] https://crrev.com/7263ff4c7fd91d83af303428614392fa610b2f8c/third_party/blink/renderer/platform/graphics/compositing/paint_artifact_compositor.cc
[modify] https://crrev.com/7263ff4c7fd91d83af303428614392fa610b2f8c/third_party/blink/renderer/platform/graphics/compositing/paint_artifact_compositor_test.cc
[modify] https://crrev.com/7263ff4c7fd91d83af303428614392fa610b2f8c/third_party/blink/renderer/platform/graphics/compositor_element_id.cc
[modify] https://crrev.com/7263ff4c7fd91d83af303428614392fa610b2f8c/third_party/blink/renderer/platform/graphics/compositor_element_id.h
[modify] https://crrev.com/7263ff4c7fd91d83af303428614392fa610b2f8c/third_party/blink/renderer/platform/graphics/paint/property_tree_state.cc
[modify] https://crrev.com/7263ff4c7fd91d83af303428614392fa610b2f8c/third_party/blink/renderer/platform/graphics/paint/property_tree_state.h
[modify] https://crrev.com/7263ff4c7fd91d83af303428614392fa610b2f8c/third_party/blink/renderer/platform/graphics/paint/property_tree_state_test.cc
[modify] https://crrev.com/7263ff4c7fd91d83af303428614392fa610b2f8c/third_party/blink/renderer/platform/graphics/paint/ref_counted_property_tree_state.cc
[modify] https://crrev.com/7263ff4c7fd91d83af303428614392fa610b2f8c/third_party/blink/renderer/platform/graphics/paint/ref_counted_property_tree_state.h

The test was new and now it's gone as the CL was reverted. The problem no longer
exists.

The test has been relanded with the flakiness resolved.