Implement Element.scrollIntoView for scroll-behavior: smooth.

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

 // Copyright 2015 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.
 
 #ifndef RootFrameViewport_h
 #define RootFrameViewport_h
 
 #include "core/CoreExport.h"
 #include "platform/scroll/ScrollableArea.h"
 
@@ skipping 42 matching lines @@
   void DidUpdateVisualViewport();
 
   // ScrollableArea Implementation
   bool IsRootFrameViewport() const override { return true; }
   void SetScrollOffset(const ScrollOffset&,
                        ScrollType,
                        ScrollBehavior = kScrollBehaviorInstant) override;
   LayoutRect ScrollIntoView(const LayoutRect& rect_in_content,
                             const ScrollAlignment& align_x,
                             const ScrollAlignment& align_y,
+                            bool is_smooth,
                             ScrollType = kProgrammaticScroll) override;
   IntRect VisibleContentRect(
       IncludeScrollbarsInRect = kExcludeScrollbars) const override;
   bool ShouldUseIntegerScrollOffset() const override;
   bool IsActive() const override;
   int ScrollSize(ScrollbarOrientation) const override;
   bool IsScrollCornerVisible() const override;
   IntRect ScrollCornerRect() const override;
   void UpdateScrollOffset(const ScrollOffset&, ScrollType) override;
   IntSize ScrollOffsetInt() const override;
@@ skipping 14 matching lines @@
   GraphicsLayer* LayerForScrollCorner() const override;
   int HorizontalScrollbarHeight(
       OverlayScrollbarClipBehavior =
           kIgnorePlatformOverlayScrollbarSize) const override;
   int VerticalScrollbarWidth(
       OverlayScrollbarClipBehavior =
           kIgnorePlatformOverlayScrollbarSize) const override;
   ScrollResult UserScroll(ScrollGranularity, const FloatSize&) override;
   bool ScrollAnimatorEnabled() const override;
   PlatformChromeClient* GetChromeClient() const override;
+  SmoothScrollSequencer* GetSmoothScrollSequencer() const override;
   void ServiceScrollAnimations(double) override;
   void UpdateCompositorScrollAnimations() override;
   void CancelProgrammaticScrollAnimation() override;
   ScrollBehavior ScrollBehaviorStyle() const override;
   void ClearScrollableArea() override;
   LayoutBox* GetLayoutBox() const override;
   FloatQuad LocalToVisibleContentQuad(const FloatQuad&,
                                       const LayoutObject*,
                                       unsigned = 0) const final;
   RefPtr<WebTaskRunner> GetTimerTaskRunner() const final;
@@ skipping 27 matching lines @@
 
 DEFINE_TYPE_CASTS(RootFrameViewport,
                   ScrollableArea,
                   scrollableArea,
                   scrollableArea->IsRootFrameViewport(),
                   scrollableArea.IsRootFrameViewport());
 
 }  // namespace blink
 
 #endif  // RootFrameViewport_h