Implement Element.scrollIntoView for scroll-behavior: smooth.

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 <memory>
 #include "platform/animation/CompositorAnimation.h"
 #include "platform/animation/CompositorScrollOffsetAnimationCurve.h"
 #include "platform/geometry/IntSize.h"
 #include "platform/graphics/GraphicsLayer.h"
 #include "platform/scroll/ScrollableArea.h"
+#include "platform/scroll/SmoothScrollSequencer.h"
 #include "platform/wtf/PtrUtil.h"
 #include "public/platform/Platform.h"
 #include "public/platform/WebCompositorSupport.h"
 
 namespace blink {
 
 ProgrammaticScrollAnimator::ProgrammaticScrollAnimator(
     ScrollableArea* scrollableArea)
     : m_scrollableArea(scrollableArea), m_startTime(0.0) {}
 
@@ skipping 46 matching lines @@
   if (!m_startTime)
     m_startTime = monotonicTime;
   double elapsedTime = monotonicTime - m_startTime;
   bool isFinished = (elapsedTime > m_animationCurve->duration());
   ScrollOffset offset =
       blinkOffsetFromCompositorOffset(m_animationCurve->getValue(elapsedTime));
   notifyOffsetChanged(offset);
 
   if (isFinished) {
     m_runState = RunState::PostAnimationCleanup;
+    getScrollableArea()->getSmoothScrollSequencer()->notifyAnimationFinished();

[bokan, 2017/04/07 15:56:52]

What other programmatic animations is this class handling? We should make sure
we can distinguish between the ones that the sequencer needs to know about.

[sunyunjia, 2017/05/12 18:40:25]

Done.

   } else if (!m_scrollableArea->scheduleAnimation()) {
     notifyOffsetChanged(offset);
     resetAnimationState();
   }
 }
 
 void ProgrammaticScrollAnimator::updateCompositorAnimations() {
   if (m_runState == RunState::PostAnimationCleanup) {
     // No special cleanup, simply reset animation state. We have this state
     // here because the state machine is shared with ScrollAnimator which
@@ skipping 72 matching lines @@
       resetAnimationState();
       notifyOffsetChanged(m_targetOffset);
     }
   }
 }
 
 void ProgrammaticScrollAnimator::notifyCompositorAnimationFinished(
     int groupId) {
   ASSERT(m_runState != RunState::RunningOnCompositorButNeedsUpdate);
   ScrollAnimatorCompositorCoordinator::compositorAnimationFinished(groupId);
+  getScrollableArea()->getSmoothScrollSequencer()->notifyAnimationFinished();
 }
 
 DEFINE_TRACE(ProgrammaticScrollAnimator) {
   visitor->trace(m_scrollableArea);
   ScrollAnimatorCompositorCoordinator::trace(visitor);
 }
 
 }  // namespace blink