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 = ScrollBehaviorInstant) override;
   LayoutRect scrollIntoView(const LayoutRect& rectInContent,
                             const ScrollAlignment& alignX,
                             const ScrollAlignment& alignY,
-                            ScrollType = ProgrammaticScroll) override;
+                            ScrollType = ProgrammaticScroll,
+                            bool isSmooth = false) override;
   IntRect visibleContentRect(
       IncludeScrollbarsInRect = ExcludeScrollbars) 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;
   ScrollOffset getScrollOffset() const override;
@@ skipping 13 matching lines @@
   GraphicsLayer* layerForScrollCorner() const override;
   int horizontalScrollbarHeight(
       OverlayScrollbarClipBehavior =
           IgnorePlatformOverlayScrollbarSize) const override;
   int verticalScrollbarWidth(
       OverlayScrollbarClipBehavior =
           IgnorePlatformOverlayScrollbarSize) const override;
   ScrollResult userScroll(ScrollGranularity, const FloatSize&) override;
   bool scrollAnimatorEnabled() const override;
   HostWindow* getHostWindow() const override;
+  SmoothScrollSequencer* getSmoothScrollSequencer() const override;
   void serviceScrollAnimations(double) override;
   void updateCompositorScrollAnimations() override;
   void cancelProgrammaticScrollAnimation() override;
   ScrollBehavior scrollBehaviorStyle() const override;
   FrameViewBase* getFrameViewBase() override;
   void clearScrollableArea() override;
   LayoutBox* layoutBox() const override;
   FloatQuad localToVisibleContentQuad(const FloatQuad&,
                                       const LayoutObject*,
                                       unsigned = 0) const final;
@@ skipping 28 matching lines @@
 
 DEFINE_TYPE_CASTS(RootFrameViewport,
                   ScrollableArea,
                   scrollableArea,
                   scrollableArea->isRootFrameViewport(),
                   scrollableArea.isRootFrameViewport());
 
 }  // namespace blink
 
 #endif  // RootFrameViewport_h