Takeover MT initiated animations from the compositor

third_party/WebKit/Source/platform/scroll/ScrollAnimator.h

Index: third_party/WebKit/Source/platform/scroll/ScrollAnimator.h
diff --git a/third_party/WebKit/Source/platform/scroll/ScrollAnimator.h b/third_party/WebKit/Source/platform/scroll/ScrollAnimator.h
index a9e2684f24bb332343a3ae5b8e1ec8f420c75731..ea8676b3fadbd91d6775df932b0909305d408dce 100644
--- a/third_party/WebKit/Source/platform/scroll/ScrollAnimator.h
+++ b/third_party/WebKit/Source/platform/scroll/ScrollAnimator.h
@@ -43,7 +43,7 @@ namespace blink {
 class ScrollAnimatorTest;
 class CompositorAnimationTimeline;
 
-class PLATFORM_EXPORT ScrollAnimator final : public ScrollAnimatorBase {
+class PLATFORM_EXPORT ScrollAnimator : public ScrollAnimatorBase {
 public:
     explicit ScrollAnimator(ScrollableArea*, WTF::TimeFunction = WTF::monotonicallyIncreasingTime);
     ~ScrollAnimator() override;
@@ -58,6 +58,7 @@ public:
     // ScrollAnimatorCompositorCoordinator implementation.
     void tickAnimation(double monotonicTime) override;
     void cancelAnimation() override;
+    void takeoverCompositorAnimation() override;
     void resetAnimationState() override;
     void updateCompositorAnimations() override;
     void notifyCompositorAnimationFinished(int groupId) override;
@@ -67,6 +68,9 @@ public:
     DECLARE_VIRTUAL_TRACE();
 
 protected:
+    // Returns whether or not the animation was sent to the compositor.
+    virtual bool sendAnimationToCompositor();
+
     void notifyAnimationTakeover(
         double monotonicTime,
         double animationStartTime,