Implement Element.scrollIntoView for scroll-behavior: smooth.

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

Index: third_party/WebKit/Source/platform/scroll/ScrollableArea.h
diff --git a/third_party/WebKit/Source/platform/scroll/ScrollableArea.h b/third_party/WebKit/Source/platform/scroll/ScrollableArea.h
index c84eb7ca282d8345c38f621520c7c4f7b0b65f1a..706ff53573dded2633f296cc535eaf0091cf6117 100644
--- a/third_party/WebKit/Source/platform/scroll/ScrollableArea.h
+++ b/third_party/WebKit/Source/platform/scroll/ScrollableArea.h
@@ -53,6 +53,7 @@ class ProgrammaticScrollAnimator;
 struct ScrollAlignment;
 class ScrollAnchor;
 class ScrollAnimatorBase;
+class SmoothScrollSequencer;
 class CompositorAnimationTimeline;
 
 enum IncludeScrollbarsInRect {
@@ -80,6 +81,8 @@ class PLATFORM_EXPORT ScrollableArea : public GarbageCollectedMixin,
   // coordinate space.
   virtual HostWindow* getHostWindow() const { return 0; }
 
+  virtual SmoothScrollSequencer* getSmoothScrollSequencer() const { return 0; }

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

nit: return nullptr

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

Done.

+
   virtual ScrollResult userScroll(ScrollGranularity, const ScrollOffset&);
 
   virtual void setScrollOffset(const ScrollOffset&,
@@ -102,7 +105,8 @@ class PLATFORM_EXPORT ScrollableArea : public GarbageCollectedMixin,
   virtual LayoutRect scrollIntoView(const LayoutRect& rectInContent,
                                     const ScrollAlignment& alignX,
                                     const ScrollAlignment& alignY,
-                                    ScrollType = ProgrammaticScroll);
+                                    ScrollType = ProgrammaticScroll,
+                                    bool isSmooth = false);
 
   static bool scrollBehaviorFromString(const String&, ScrollBehavior&);