Implement Element.scrollIntoView for scroll-behavior: smooth.

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

 /*
  * Copyright (C) 2006, 2007, 2009, 2010 Apple Inc. All rights reserved.
  * Copyright (C) 2010 Nokia Corporation and/or its subsidiary(-ies)
  *
  * Redistribution and use in source and binary forms, with or without
  * modification, are permitted provided that the following conditions
  * are met:
  * 1. Redistributions of source code must retain the above copyright
  *    notice, this list of conditions and the following disclaimer.
  * 2. Redistributions in binary form must reproduce the above copyright
@@ skipping 177 matching lines @@
   bool find(const String&,
             bool case_sensitive,
             bool backwards,
             bool wrap,
             bool whole_word,
             bool search_in_frames,
             bool show_dialog) const;
 
   // FIXME: ScrollBehaviorSmooth is currently unsupported in VisualViewport.
   // crbug.com/434497
+  void scrollViewportTo(ScrollableArea*,
+                        const ScrollOffset&,
+                        ScrollBehavior) const;
   void scrollBy(double x, double y, ScrollBehavior = kScrollBehaviorAuto) const;
   void scrollBy(const ScrollToOptions&) const;
   void scrollTo(double x, double y) const;
   void scrollTo(const ScrollToOptions&) const;
   void scroll(double x, double y) const { scrollTo(x, y); }
   void scroll(const ScrollToOptions& scroll_to_options) const {
     scrollTo(scroll_to_options);
   }
   void moveBy(int x, int y) const;
   void moveTo(int x, int y) const;
@@ skipping 177 matching lines @@
   return status_;
 }
 
 inline String LocalDOMWindow::defaultStatus() const {
   return default_status_;
 }
 
 }  // namespace blink
 
 #endif  // LocalDOMWindow_h