The following revision refers to this bug:
  https://chromium.googlesource.com/chromium/src.git/+/feb2f7ea63e78f7cbfd219beaef7440d41f1aef8

commit feb2f7ea63e78f7cbfd219beaef7440d41f1aef8
Author: Yi Gu <yigu@chromium.org>
Date: Thu Sep 13 03:27:40 2018

[animation-worklet] Update composited properties on main thread

A composited worklet animation is updated on the worklet as requested by
the compositor. This CL adds a new path to allow main thread to request
its output time value. The output time value is used to drive the
keyframe effect on main thread and update the computed style.

Detailed changes in the CL:
Animator maintains its latest output so it can be requested.
AnimationWorkletInput now includes a list of 'Peeked' animations.
Simplify WorkletAnimationController by no longer maintaining two
animations lists (composited and main) since most of its operations do
not discriminate.

Bug:  881868 
Cq-Include-Trybots: luci.chromium.try:android_optional_gpu_tests_rel;luci.chromium.try:linux_layout_tests_slimming_paint_v2;master.tryserver.blink:linux_trusty_blink_rel
Change-Id: I722db0260cb1efba42260d867d9f04cdd6edf115
Reviewed-on: https://chromium-review.googlesource.com/1213475
Reviewed-by: Stephen McGruer <smcgruer@chromium.org>
Reviewed-by: Majid Valipour <majidvp@chromium.org>
Cr-Commit-Position: refs/heads/master@{#590910}
[modify] https://crrev.com/feb2f7ea63e78f7cbfd219beaef7440d41f1aef8/cc/trees/layer_tree_mutator.cc
[modify] https://crrev.com/feb2f7ea63e78f7cbfd219beaef7440d41f1aef8/cc/trees/layer_tree_mutator.h
[add] https://crrev.com/feb2f7ea63e78f7cbfd219beaef7440d41f1aef8/third_party/WebKit/LayoutTests/virtual/threaded/fast/animationworklet/peek-updated-composited-property-on-main-expected.txt
[add] https://crrev.com/feb2f7ea63e78f7cbfd219beaef7440d41f1aef8/third_party/WebKit/LayoutTests/virtual/threaded/fast/animationworklet/peek-updated-composited-property-on-main.html
[modify] https://crrev.com/feb2f7ea63e78f7cbfd219beaef7440d41f1aef8/third_party/WebKit/LayoutTests/virtual/threaded/fast/animationworklet/worklet-animation-style-update-expected.txt
[modify] https://crrev.com/feb2f7ea63e78f7cbfd219beaef7440d41f1aef8/third_party/blink/renderer/core/animation/worklet_animation_base.h
[modify] https://crrev.com/feb2f7ea63e78f7cbfd219beaef7440d41f1aef8/third_party/blink/renderer/core/animation/worklet_animation_controller.cc
[modify] https://crrev.com/feb2f7ea63e78f7cbfd219beaef7440d41f1aef8/third_party/blink/renderer/core/animation/worklet_animation_controller.h
[modify] https://crrev.com/feb2f7ea63e78f7cbfd219beaef7440d41f1aef8/third_party/blink/renderer/modules/animationworklet/animation_worklet_global_scope.cc
[modify] https://crrev.com/feb2f7ea63e78f7cbfd219beaef7440d41f1aef8/third_party/blink/renderer/modules/animationworklet/animator.h
[modify] https://crrev.com/feb2f7ea63e78f7cbfd219beaef7440d41f1aef8/third_party/blink/renderer/modules/animationworklet/worklet_animation.cc
[modify] https://crrev.com/feb2f7ea63e78f7cbfd219beaef7440d41f1aef8/third_party/blink/renderer/modules/animationworklet/worklet_animation.h