Run smooth scroll animations on the compositor when possible

This CL implements "immediate retargeting" shown in the following diagram:
https://docs.google.com/drawings/d/1z76m-GMDgLI-clkfroLJ-5yhsHkmriZr_swP0kn5iw4

This CL does the following
- Add a new state to ScrollAnimatorCompositorCoordinator to update the target
offset on the compositor
- Use the ScrollAnimatorCompositorCoordinator to schedule anim
- Add plumbing from the animators to the animation controller to abort
animations

Sample test pages:
yashmalik.com/nested_scroll_mousewheel_listener.html
yashmalik.com/nested_scroll_mousewheel_listener_15ms_janky.html (tight loop in RAF)

BUG=552556
CQ_INCLUDE_TRYBOTS=tryserver.blink:linux_blink_rel

Review URL: https://codereview.chromium.org/1534813004

Cr-Commit-Position: refs/heads/master@{#366685}

1 files changed, 1 insertions, 0 deletions

diff --git a/cc/blink/web_layer_impl.h b/cc/blink/web_layer_impl.h
index a1b762b..3fd0bcc 100644
--- a/cc/blink/web_layer_impl.h
+++ b/cc/blink/web_layer_impl.h
@@ -113,6 +113,7 @@ class WebLayerImpl : public blink::WebLayer {
   void removeAnimation(int animation_id,
                        blink::WebCompositorAnimation::TargetProperty) override;
   void pauseAnimation(int animation_id, double time_offset) override;
+  void abortAnimation(int animation_id) override;
   bool hasActiveAnimation() override;
   void setForceRenderSurface(bool force) override;
   void setScrollPositionDouble(blink::WebDoublePoint position) override;