First programmatic smooth scroll should run on the compositor if it can

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

 // Copyright 2014 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #include "platform/scroll/ProgrammaticScrollAnimator.h"
 
 #include "platform/animation/CompositorAnimation.h"
 #include "platform/animation/CompositorScrollOffsetAnimationCurve.h"
 #include "platform/geometry/IntPoint.h"
 #include "platform/graphics/CompositorFactory.h"
@@ skipping 103 matching lines @@
 
         m_compositorAnimationId = 0;
         m_compositorAnimationGroupId = 0;
         if (m_runState == RunState::WaitingToCancelOnCompositor) {
             resetAnimationState();
             return;
         }
     }
 
     if (m_runState == RunState::WaitingToSendToCompositor) {
+        if (!m_compositorAnimationAttachedToLayerId)
+            reattachCompositorPlayerIfNeeded(getScrollableArea()->compositorAnimationTimeline());
+
         bool sentToCompositor = false;
 
         if (!m_scrollableArea->shouldScrollOnMainThread()) {
             OwnPtr<CompositorAnimation> animation = adoptPtr(CompositorFactory::current().createAnimation(*m_animationCurve, CompositorTargetProperty::SCROLL_OFFSET));
 
             int animationId = animation->id();
             int animationGroupId = animation->group();
 
             if (addAnimation(animation.release())) {
                 sentToCompositor = true;
@@ skipping 41 matching lines @@
     ScrollAnimatorCompositorCoordinator::compositorAnimationFinished(groupId);
 }
 
 DEFINE_TRACE(ProgrammaticScrollAnimator)
 {
     visitor->trace(m_scrollableArea);
     ScrollAnimatorCompositorCoordinator::trace(visitor);
 }
 
 } // namespace blink