Query compositing state only from UpdateAnimationState

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

Index: third_party/WebKit/Source/platform/scroll/ScrollAnimator.cpp
diff --git a/third_party/WebKit/Source/platform/scroll/ScrollAnimator.cpp b/third_party/WebKit/Source/platform/scroll/ScrollAnimator.cpp
index 364765f85b02268e8e5f9680ddc95035ce66028b..017acf5a26bc216ea331ce295cb11af3f866ebf8 100644
--- a/third_party/WebKit/Source/platform/scroll/ScrollAnimator.cpp
+++ b/third_party/WebKit/Source/platform/scroll/ScrollAnimator.cpp
@@ -187,14 +187,8 @@ bool ScrollAnimator::willAnimateToOffset(const FloatPoint& targetPos)
     m_targetOffset = targetPos;
     m_startTime = m_timeFunction();
 
-    if (registerAndScheduleAnimation()) {
-        if (m_scrollableArea->shouldScrollOnMainThread()) {
-            createAnimationCurve();
-            m_runState = RunState::RunningOnMainThread;
-        } else {
-            m_runState = RunState::WaitingToSendToCompositor;
-        }
-    }
+    if (registerAndScheduleAnimation())
+        m_runState = RunState::WaitingToSendToCompositor;
 
     return true;
 }
@@ -304,13 +298,6 @@ void ScrollAnimator::createAnimationCurve()
 void ScrollAnimator::updateCompositorAnimations()
 {
     ScrollAnimatorCompositorCoordinator::updateCompositorAnimations();
-    if (m_runState == RunState::RunningOnMainThread) {
-        // We add a temporary main thread scrolling reason so that subsequent
-        // scrolls get handled on the main thread. This is removed when the
-        // animation is finished in ::tickAnimation.
-        addMainThreadScrollingReason();
-        return;
-    }
 
     if (m_runState == RunState::PostAnimationCleanup) {
         postAnimationCleanupAndReset();