[Code Health] Cleanup some ScrollAnimator members

This patch removes one unused override function and makes some variables
private.

Bug: None
Change-Id: Iffe10827abd4ef5fcbccc70393fa6d4167f223df
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/1711975Reviewed-by: David Bokan <bokan@chromium.org>
Commit-Queue: Yi Gu <yigu@chromium.org>
Cr-Commit-Position: refs/heads/master@{#680178}

third_party/blink/renderer/core/scroll/scroll_animator.cc

@@ -431,27 +431,6 @@ void ScrollAnimator::NotifyCompositorAnimationFinished(int group_id) {
     std::move(on_finish_).Run();
 }
 
-void ScrollAnimator::NotifyAnimationTakeover(
-    double monotonic_time,
-    double animation_start_time,
-    std::unique_ptr<cc::AnimationCurve> curve) {
-  // If there is already an animation running and the compositor asks to take
-  // over an animation, do nothing to avoid judder.
-  if (HasRunningAnimation())
-    return;
-
-  cc::ScrollOffsetAnimationCurve* scroll_offset_animation_curve =
-      curve->ToScrollOffsetAnimationCurve();
-  ScrollOffset target_value(scroll_offset_animation_curve->target_value().x(),
-                            scroll_offset_animation_curve->target_value().y());
-  if (WillAnimateToOffset(target_value)) {
-    animation_curve_ = std::make_unique<CompositorScrollOffsetAnimationCurve>(
-        scroll_offset_animation_curve);
-    start_time_ =
-        base::TimeTicks() + base::TimeDelta::FromSecondsD(animation_start_time);
-  }
-}
-
 void ScrollAnimator::CancelAnimation() {
   ScrollAnimatorCompositorCoordinator::CancelAnimation();
   if (on_finish_)

third_party/blink/renderer/core/scroll/scroll_animator.h

@@ -137,14 +137,6 @@ class CORE_EXPORT ScrollAnimator : public ScrollAnimatorBase {
   // Returns whether or not the animation was sent to the compositor.
   virtual bool SendAnimationToCompositor();
 
-  void NotifyAnimationTakeover(double monotonic_time,
-                               double animation_start_time,
-                               std::unique_ptr<cc::AnimationCurve>) override;
-
-  std::unique_ptr<CompositorScrollOffsetAnimationCurve> animation_curve_;
-  const base::TickClock* const tick_clock_;
-  base::TimeTicks start_time_;
-
  private:
   // Returns true if the animation was scheduled successfully. If animation
   // could not be scheduled (e.g. because the frame is detached), scrolls
@@ -162,6 +154,10 @@ class CORE_EXPORT ScrollAnimator : public ScrollAnimatorBase {
   // because we are already at targetPos.
   bool WillAnimateToOffset(const ScrollOffset& target_pos);
 
+  std::unique_ptr<CompositorScrollOffsetAnimationCurve> animation_curve_;
+  const base::TickClock* const tick_clock_;
+  base::TimeTicks start_time_;
+
   ScrollOffset target_offset_;
   ScrollGranularity last_granularity_;