Basic ScrollTimeline implementation for Animation Worklet

third_party/WebKit/Source/core/animation/AnimationTimeline.h

Index: third_party/WebKit/Source/core/animation/AnimationTimeline.h
diff --git a/third_party/WebKit/Source/core/animation/AnimationTimeline.h b/third_party/WebKit/Source/core/animation/AnimationTimeline.h
index 7a28053fe7b9b8138bf1750c1a21ee2932366793..870620834cdd4eb212d5e2a88d9aaa1eacf52866 100644
--- a/third_party/WebKit/Source/core/animation/AnimationTimeline.h
+++ b/third_party/WebKit/Source/core/animation/AnimationTimeline.h
@@ -83,10 +83,10 @@ class CORE_EXPORT AnimationTimeline
     return !animations_needing_update_.IsEmpty();
   }
   double ZeroTime();
-  double currentTime(bool& is_null);
-  double currentTime();
-  double CurrentTimeInternal(bool& is_null);
-  double CurrentTimeInternal();
+  virtual double currentTime(bool& is_null);
+  virtual double currentTime();
+  virtual double CurrentTimeInternal(bool& is_null);
+  virtual double CurrentTimeInternal();
   void setCurrentTime(double, bool is_null);
   void SetCurrentTimeInternal(double);
   double EffectiveTime();
@@ -110,7 +110,7 @@ class CORE_EXPORT AnimationTimeline
   void Wake();
   void ResetForTesting();
 
-  DECLARE_TRACE();
+  DECLARE_VIRTUAL_TRACE();
 
  protected:
   AnimationTimeline(Document*, PlatformTiming*);