Implement Element.scrollIntoView for scroll-behavior: smooth.

third_party/WebKit/Source/core/frame/FrameView.h

Index: third_party/WebKit/Source/core/frame/FrameView.h
diff --git a/third_party/WebKit/Source/core/frame/FrameView.h b/third_party/WebKit/Source/core/frame/FrameView.h
index 7de2782196fa820234d0b03a93f3845bbfa71378..2de09d2b07f37f06d4aef45d459d0b71899b8a6d 100644
--- a/third_party/WebKit/Source/core/frame/FrameView.h
+++ b/third_party/WebKit/Source/core/frame/FrameView.h
@@ -46,6 +46,7 @@
 #include "platform/geometry/LayoutRect.h"
 #include "platform/graphics/Color.h"
 #include "platform/graphics/GraphicsLayerClient.h"
+#include "platform/scroll/ProgrammaticScrollCoordinator.h"
 #include "platform/scroll/ScrollTypes.h"
 #include "platform/scroll/Scrollbar.h"
 #include "public/platform/ShapeProperties.h"
@@ -452,12 +453,16 @@ class CORE_EXPORT FrameView final
   LayoutRect scrollIntoView(const LayoutRect& rectInContent,
                             const ScrollAlignment& alignX,
                             const ScrollAlignment& alignY,
-                            ScrollType = ProgrammaticScroll) override;
+                            ScrollType = ProgrammaticScroll,
+                            ScrollBehavior = ScrollBehaviorAuto) override;
 
   // The window that hosts the FrameView. The FrameView will communicate scrolls
   // and repaints to the host window in the window's coordinate space.
   HostWindow* getHostWindow() const;
 
+  ProgrammaticScrollCoordinator* getProgrammaticScrollCoordinator()
+      const override;
+
   typedef HeapHashSet<Member<Widget>> ChildrenWidgetSet;
 
   // Functions for child manipulation and inspection.