Implement Element.scrollIntoView for scroll-behavior: smooth.

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

Index: third_party/WebKit/Source/platform/scroll/ProgrammaticScrollAnimator.cpp
diff --git a/third_party/WebKit/Source/platform/scroll/ProgrammaticScrollAnimator.cpp b/third_party/WebKit/Source/platform/scroll/ProgrammaticScrollAnimator.cpp
index b717e08a653fad1d135766e18a01070cddfca373..0c377567ec80ab609c62216752cd280e18e78744 100644
--- a/third_party/WebKit/Source/platform/scroll/ProgrammaticScrollAnimator.cpp
+++ b/third_party/WebKit/Source/platform/scroll/ProgrammaticScrollAnimator.cpp
@@ -10,6 +10,7 @@
 #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"
@@ -30,7 +31,10 @@ void ProgrammaticScrollAnimator::ResetAnimationState() {
 
 void ProgrammaticScrollAnimator::NotifyOffsetChanged(
     const ScrollOffset& offset) {
-  ScrollOffsetChanged(offset, kProgrammaticScroll);
+  if (sequenced_for_smooth_scroll_)

[bokan, 2017/06/07 17:56:00]

nit: scroll_type = sequenced_for_smooth_scroll ? kSequenced : kProgrammatic

[sunyunjia, 2017/06/07 18:34:10]

Done.

+    ScrollOffsetChanged(offset, kSequencedSmoothScroll);
+  else
+    ScrollOffsetChanged(offset, kProgrammaticScroll);
 }
 
 void ProgrammaticScrollAnimator::ScrollToOffsetWithoutAnimation(
@@ -39,12 +43,15 @@ void ProgrammaticScrollAnimator::ScrollToOffsetWithoutAnimation(
   NotifyOffsetChanged(offset);
 }
 
-void ProgrammaticScrollAnimator::AnimateToOffset(const ScrollOffset& offset) {
+void ProgrammaticScrollAnimator::AnimateToOffset(
+    const ScrollOffset& offset,
+    bool sequenced_for_smooth_scroll) {
   if (run_state_ == RunState::kPostAnimationCleanup)
     ResetAnimationState();
 
   start_time_ = 0.0;
   target_offset_ = offset;
+  sequenced_for_smooth_scroll_ = sequenced_for_smooth_scroll;
   animation_curve_ = CompositorScrollOffsetAnimationCurve::Create(
       CompositorOffsetFromBlinkOffset(target_offset_),
       CompositorScrollOffsetAnimationCurve::kScrollDurationDeltaBased);
@@ -76,6 +83,7 @@ void ProgrammaticScrollAnimator::TickAnimation(double monotonic_time) {
 
   if (is_finished) {
     run_state_ = RunState::kPostAnimationCleanup;
+    AnimationFinished();
   } else if (!scrollable_area_->ScheduleAnimation()) {
     NotifyOffsetChanged(offset);
     ResetAnimationState();
@@ -116,7 +124,11 @@ void ProgrammaticScrollAnimator::UpdateCompositorAnimations() {
 
     bool sent_to_compositor = false;
 
-    if (!scrollable_area_->ShouldScrollOnMainThread()) {
+    // TODO(sunyunjia): Sequenced Smooth Scroll should also be able to
+    // scroll on the compositor thread. We should send the ScrollType
+    // information to the compositor thread.

[bokan, 2017/06/07 17:56:53]

Oh, and please file a bug to make this work with compositor. Add the bug # here.

[sunyunjia, 2017/06/07 18:34:10]

Done.

+    if (!scrollable_area_->ShouldScrollOnMainThread() &&
+        !sequenced_for_smooth_scroll_) {
       std::unique_ptr<CompositorAnimation> animation =
           CompositorAnimation::Create(
               *animation_curve_, CompositorTargetProperty::SCROLL_OFFSET, 0, 0);
@@ -169,6 +181,16 @@ void ProgrammaticScrollAnimator::NotifyCompositorAnimationFinished(
     int group_id) {
   DCHECK_NE(run_state_, RunState::kRunningOnCompositorButNeedsUpdate);
   ScrollAnimatorCompositorCoordinator::CompositorAnimationFinished(group_id);
+  AnimationFinished();
+}
+
+void ProgrammaticScrollAnimator::AnimationFinished() {
+  if (sequenced_for_smooth_scroll_) {
+    sequenced_for_smooth_scroll_ = false;
+    if (SmoothScrollSequencer* sequencer =
+            GetScrollableArea()->GetSmoothScrollSequencer())
+      sequencer->RunQueuedAnimations();
+  }
 }
 
 DEFINE_TRACE(ProgrammaticScrollAnimator) {